"Painless" Doc Jhonson, or how to kill your commander

[Ghill]

This is just theory mind you, I have never gone for a wish strategy and I hardly use undead so I might be overlooking something, but...

If casting wish is on the table, why don't you just use a wish to cure the wight of all afflictions?

Alternatively, summon a unit with heal (if you can) to get rid of the wights wounds.

I think all of the cleanest kills are already suggested.