Resurrection Signet is a one-shot skill (it can only be used
once per mission) that takes up a full slot on your skill bar, effectively meaning you're restricted to seven worthwhile skills. It has a ridiculously long cast, and resurrected allies come back with only a sliver of health, so if they're a high-priority target they're not going to survive once you raise them, anyway. Resurrection Signet, even in PvE, is trash. Absolutely worthless.
Y'know, you're asking a lot of really simple questions as of late. Rather than clogging up The Riverside Inn, post in
Questions & Answers, preferably putting all your questions into one thread. It prevents The Inn from getting clogged up with stuff like this, mate.