In the last pair of DRK reviews I read they were explaining Living Dead pretty detailed: it's a 10 seconds buff whereas your HP cannot fall below 1, like Holmgang without the bind, if you take more damage though a 10 second debuff, still keeping the Holmgang effect, starts and if you don't touch the 100% HP before it runs out you'll die.

It'd make Benediction handy for Living Dead.