In PvP battles anyone can ress anyone else and they are back into it within seconds.

Heres my fix for it:

It should be that every time you die in a PvP battle (which would have to be a time period or location), it takes more people to ress you.

So die once, any person can res you.
Die twice, two people have to res you
Die three times, three people have to res you.
Die ... you get the idea. Cap it at 5 or 6 maybe.

This answers all angles for requirements and puts the onus of the guild to keep each other alive.

A moment of brilliance I must say

Cheers
Shane