If you are a chaotic Knight, Excalibur should evade your grasp, being impossible to pick up as if it were a crossaligned quest artifact.

(Additional rule for EvilHack: Dirge should evade the grasp of lawful knights.)

Chaotic Knights should still have a set of role penalties, not necessarily the same caitiff ones as lawful Knights, and maybe not as many, but still something that emphasizes that a chaotic knight is still a knight and is expected to have some pragmatic self-discipline.

The drain life spell heals you with some of the HP you drained from your target, possibly even increasing maximum HP by one point if it is full (though this is probably too powerful).

The healing isn’t intended for anyone who can cast it; it would require you to have a certain amount of attack skill and possibly be chaotic.

Chaotic gods in FIQHack should sometimes grant potions of wonder as a sacrifice gift.

Chaotic Archeologists gain alignment for taking historic statues and moving them off-level. Neutral Archeologists gain alignment from bringing historic statues into their quest home. (Lawful ones get nothing, because it’s right for them to leave the statues where they were.)

A chaotic Cartomancer who performs a same-race sacrifice gets not a peaceful Juiblex or Yeenoghu, but a card of summon Juiblex or Yeenoghu.

Chaotic same-race sacrifice demon summoning causes the demon to give you a nice item or some gold when they appear.