Death is one of two branching paths from Wraith, the other being Wight. Deaths have all the same advantages and disadvantages that Wraiths do. However, they are also able to poison enemies. In addition they do a bit more damage than their counterparts, the Wights.
In Disciples 2, in both Dark Prophecy and Gallean's Return, Death has 60 initiative, as much as the Wight, and with 100 damage plus 20 poison damage is able to singlehandedly overcome the strongest mages, but in Rise of the Elves its initiative is lowered to 40, thus deaths become more vulnerable to spellcasters, especially if buffed for initiative.