An entertaining read. It's good to see some backstory, but the odds of such a talent are incredibly low.
We're talking 5% or players having a talent. Of those, there might be 100 talents or more from the trivial crafting or professional aptitudes to the rare magic skills.
Let's suppose there's a 1% chance of a talent being necromancy. That puts you at a 5% of 1% chance of having it ie 0.05% or 1 in 2,000.
The next catch is that to activate or discover you have a talent requires the right circumstances. For a rare talent like that, it might require an evil alignment, specific bardic skills to read rather than the usual deviancy, as well as a certain artifact which every other would be necro plans to steal from you. Your odds of discovering and activating the skill mught be 10%.
Your total odds now are 0.005% or 1 in 20,000 during each lifetime, so don't plan your game around it.