Vampire Overhaul (ver. 2, OP updated!)

[locusts]

Before you have access to thralls, the return from the dead is meant to be accidental, which is a recurring plot point in vampire stories. A crafty vampire could use bleeding weapons to increase the chance of that happening, but given the amount of blood spilled all over the floor in an average round, there's a not unreasonable chance of that happening. I don't know where you got the idea that someone apart from a thrall, or perhaps another antagonist, was meant to do it willingly.