Now that is an experience we should be terrified of. All skeletons are fast skeletons, so none of that slow, shuffling business. They know how to use tools, at least swords and shields. They can also dance and create music (at least percussive music) so they have creativity and artistic verve.
So by my thaumatological analysis (and becoming a subject authority by watching lots of movies and a few animations with skeletons in them), once the undead cast off the flesh that holds their true intellect back, they metamorphosise from slow, dull zombies to terrifying, flesh-rending, tool-using reavers
Since they have that creative streak as well, it’s only a matter of time before they figure out how to use guns. They’ll be much harder to fight then, as their lack of flesh makes them much harder to hit with return fire.
Don’t be giving them ideas! There’s a skeleton inside each of us, reading this, formulating plans.