Thief - hits against an enemy have a chance to come out of his clip

Light Fingers - reload around the same time as someone you emptied a clip into and some of his bullets go into your clip.

Chameleon Weapon can switch type: auto, pulse, scout. The 2 other options appear as squares to the right of the current selected primary square. You have the usual ammo penalty except if you switch to the type of weapon equipped by your last kill. That may be on a timer from when you killed him.