For the thing to work, from has to make these enemies walk a random path or some of them facing their backs.Then you can go on stealth mode and use your daggers/critical weapons for backstabbing them. Arrows and spells can work the same way, boosting the critical damage while on stealth mode.This idea can make assassin, sneaky builds more fun for PvE.
For PvP, stealth mode wouldn't be as effective unless a completely invisible spell or ring can hide you from players. This mode can also mean that backstabs aren't as powerful as when done in stealth mode, or maybe can't be done at all. If both backstabs can be done then the stealth mode animation has a different animation than the normal backstab.