1) There's a glitch in their attack, the projectile they send hits you faster than you see it coming. I often happen to see Devilites hit me right "below" my shield when their projectile just doesn't seem to be reaching me yet
2) It occurs in the following case: when there's a Devilite turned into a "strong demon" (the glowing ones) and a boss left, that I kill the strong one, the boss turns back into a normal Devilite and says to himself, even though he's no longer a boss, a message that changes its class.
Would love it if those bugs were confirmed by some other players and eventually checked! Thanks.