A general dummy guide for those who wants to learn what kills and what doesn't kill a Yoma or a Awakaned Being. First we'll study Yoma and then move onto studying about Awakened Beings.

Yoma
Yomas are pretty common fiends and most often they're biggest advantage is the fact that they can disguise themself pretty good amongst a crowd of human. How this ability is gained and whats necessary for them to perform it is rather left as pure mystery but if Raki's circumstances were of any indicator I would think a Yoma generally requires to consume a mortal alive before being able to change their shape into the target creature. Yoma that was posing as Raki's brother was claiming a part of Raki's brother was crying for Raki hence the Yoma was shedding tears as he was about to deal the death blow. Another theory is that Yomas are like a parasite, a virus transmitted via either physical contact or mayhaps by a disease like spread in the winds, should that be the case its arguable that the process of turning into a Yoma is like a disease. But what of the two minds? The yoma took over the body but Raki's brother's conscience still remain to a degree? Does that vaguely indicate that the Yoma actually had a physical body of its own before taking possession of Raki's brother? That would then pose the question had it been a different entity or a alter ego created from contracting the disease? As displayed Yomas have physical prowess that far surpass normal humans and most have the skills to extend their nails like a projectile with minor differences in physical forms in some cases ie. Wings. They don't seem to have a great deal of armor like the awakend beings but from mere appearance it looks like a run of the mill thrust from a hoe or pitchfork wont make do with Yomas. Some can even grow really strong so much that it can hold its own against a group of armed trained soldiers as well as the weaker warriors of Claymore Organization.

What can kill them?
Obviously with the amount of strength a Claymore has at his/her disposal its quite possible that they might choose a much heavier weapons as opposed to the lighter weapons. Reasons are quite simple in that they can swing a heavy weapon almost as fast or if not as fast as any other weapon. To them a weight and shape of a melee weapon should not really make much difference to them in application. But as expected a hardness as well as the raw power of a heavier weapon definitely will outbest a lighter weapon in term of destructiveness especiall if both weapons can be swung or thrusted just as fast with great accuracy. Clare's fight with the slightly stronger Yoma in Rabona proves this as her attacks with dagger class weapons hardly phased the Yoma and it appeared to have recovered very easily in their next encounter. I think there really is a special reasons as to why a Claymore wields a claymore sword. Usually if not always one accurate swing can cleave off a arm or a head if the hit connected. Since their attack speed and drawback is hardly negligible, using the longer reach of a claymore and the hard solid heavy steel cleaves it right off with a clean cut. What can ultimately kill them? I think any living things require blood to continue their existence so I would find it logical for the Yoma to die easily from either a mortal wound that drain them of alot of their blood (An example would be possibly losing a limb, a long slash wound that dig deeply against their core torso?) or as Elcura suggested a simple dismantling of their head seems to also work well. Greatly damaging their internal organs with a thrust from their claymores also appears to do good work on these species as opposed to dealing a damage with lighter weapons like daggers or spears/arrows. Again their claymores have length, I'd imagine being stabbed through your body with a claymore will prove more fatal than the formers i mentioned before as it also gives them little to no chance of closing up the wound let alone much of a choice to evade with a claymore stuck on their torso and if pulled out no doubt the big hole across their abdomen will no doubt burst open with alot of blood. Being hit by arrows is quite different in that arrows can pierce so much but its inifinitely easier to outlive a arrow wound than a full thrust with a claymore. A bow and arrow also has lower attack speed since the damage is dependent on the weapon itself. Strings might snap and the drawback is you have to pull an arrow from the quiver to start attacking again, draw the string back and aim then fire and lastly limits you to the number of arrows you might have on you and thinking logically a warriors like claymores wont be wearing alot of quivers on their inventory. Daggers are faster and allows direct melee combat so the weapon's damage is totally dependent on the user, however with the inferior length it can only thrust so far in comparison to the claymore which has enough length and more to impale right through a body. If anything came close to the deadliness of a claymore it would either be a equally heavy weapon like a great axe or perhaps the use of two one handed swords? I'm sure there are others out there that performs the kill with similar efficiecy.

Awakened Beings Incomplete
Much more advanced and smarter than the Yomas. The fact that these guys had been previous Claymores must also mean they inherited the same skills, battle wits as well as far more knowledge when it comes to killing things. Having been a claymore before probably helps them understand their enemies far better than anyone and its quite possible they know the weaknesses even your not quite aware of since they are your senpais afterall. Now I've categorised them in Incomplete and Complete, I'll go into detail soon. There appears to be a big power difference between Incomplete Awakened Beings and Complete awakends. Not to mention the Completely Awakened ones seem to be able to hold in their primal instinct to feed unlike the Incompletes who retain not only the primal hunger but their savage appearances as Awakened Beings. Almost all Awakened Beings also seems to have a harder skin/plating that acts as armor against threats like steel being penetrated into their bodies. But unlike the C-Awakeneds, I-Awakeneds lose the ability to use the specific skill they held as Claymores which probably could be recovered once they are more experienced to be classified as C-Awakeneds. Example would be Ophelia who displayed she no longer uses the signature skill Rippling Blade to attack upon Awakening. Now then how to kill these beings, as similar to killing a yoma you must either make them bleed to death which isn't necessarily a viable option especially since they are far superior in strength and wisdom to Yomas hence prolonged fight may turn to their favor instead hence the only option seems to be to pierce through their armor and deal a deadly blow into their internal organs, cut them up in fine pieces, or as before mentioned kill the head to neutralize hostile actions completely. For more obvious reasons than last time, a Awakened Being has armor and more likely will be on a different level of speed so targetting them with projectile weapons may prove very futile and considering their armor its highly possible projectiles will be shrugged off without doing much damage should it connect. Light weapons like short swords or dagger lack the length and raw power behind the steel to propery cut up a massive awakened being nor plunge deep enough for them to feel any significant pain within their internal systems. Such circumstances really restricts a claymore to choose their weapons with following characteristics.

Does it have length?
1. Can it withstand impact after impact against solid skin armor of awakened beings?
2. Will it break if at all?
3. Is it ammo reliant?

Awakened Beings Complete
These are awakened beings that seems able to hold their human like image. They can somewhat manage for prolonged time and restrain from eating humans constantly unlike their Incomplete comrades. Also if Pieta's yoki manipulator was evidence enough its safe to believe that they can still use the same specific skill they were strong in even after awakening as well as in their human form. The fact that they not only can fight very well in their evolved state already puts them on a different level than the Incompletes, and its highly possible from looking at that given example a Awakened Being can still hold powers they had prior to Awakening which makes these type of creatures a great nuisance to hunt down. An example would be something like had someone who can hide their yoki near perfection like Raphaela became a Awakened Being Complete, its possible that she can retain her human form, have all the benefits of a awakened being starting with the greater amount of yoki, restrain her gut eating habits, AND hide her yoki just as well or even better than while she was still a claymore. These creatures should be slayed in the same manner as Awakened Beings Incompletes since more often than not if it engaged itself in a serious battlemode chances are its likely that the fight will end up with the awakened being transforming into thier monstrous appearance. Its also shown that these guys can partially transform their limbs as they wish especially if they are among stronger breeds (like a former single digit, Isley? Rigald? Duph?). These creatures are much more deadly than any other and the one superior to them are very rare, the manga providing no more than 5 of them in the series. A scary force to be reckoned with even for a veteran higher digits.

Abyssal Ones
These creatures on terms of power level is off the charts and suffice to say no matter how many run of the mill Awakened Being Completes you assign them to slay a Abyssal One, it proves that the Abyssal Ones are on a totally different league. Isley had sent a dozen? to supposedly slay Riful but they were all annhilated with hardly a scratch on both Riful and Duph. Noticeably a Awakened Being Complete fell in one hit KO with Riful merely transforming her arm to perform the kill so its quite possible for a average claymore the best thing to do in the presence of a abyssal one is to run. So far it was shown that not even a single digit with a rank Number 3 can harm or let alone put up much of a resistence against these creatures. Often regardless of ranks Claymores are toyed with by Abyssal Ones if they put a effort to the fight at all. An Abyssal One is slayable not by conventional weapons forged with steel, that alone cannot kill and its safe to assume they can only be killed by another Abyssal One or a creature of equal and higher powers than a Abyssal One. Almost a guaranteed death awaits Claymores if their true motives were to try and slay it and escaping the creature is relatively harder too.

If they stand still and you poke them hard with a stick, eventually they will die. As far as I understand few things, even Abyssal One might not survive volcano eruption - always come up with some unconventional means of fight.