The fetishes that give special affects show up as affects with -1 timers in your affect list.

Detect invis is pretty obvious.
Ears of the bat is what gives the detect sneak, while the helpfile suggests you need to see them to detect sneak you can here someones coming and going.
Demon sight or sight of the dead is the affect that gives you detect all in the orc village. It only lets you see people who are in places that orcs can use hide though.

Ear fetish gives the ears of the bat and like awareness or something (not clear what that did)
Eye fetish gives the detect invis and sight of the dead
heart fetish gives you a nice boost to regen, though I almost never used it.
the others just give you pure stats, not so much hit/dam/str but lots of saves, morale, and hp/mana