Since Energy Ring lies on my dead body, does that mean I will get resurrected when someone picks it up?
Correct, assuming of course, the player in question actually enters your tile to obtain Energy Ring, and doesn't use other Relics to pick up that item from a distance.

Call me stupid, but what does "Terrifying! (waiting on Fight/Assault...)" mean?
It means that the Wendigo Fangs were used by the user and is still in effect. Imo >_>
What Submachine said. Terrifying = until the player successfully uses Fight/Assault stance, the buff is still on them.