For those of you who can't remember IM3 and don't want to rewatch that film, some quick feats Killian to refresh your memory:
Fast enough to dodge repulsor shots after they are fired:
Superhuman strength and durability that allowed him to match multiple Iron Man suits, plus a healing factor that repaired damage almost immediately:
He does briefly break his arm here, but he also destroys the forearm of Tony's suit in the process. His healing factor was also good enough to regrow a missing limb in the space of a minute or two earlier as well.
And in terms of damage output, on top of being able to breath fire, his strength coupled with the extreme temperatures he could generate allowed him to do this: