Plot holes (spoilers included) in RotE

[Nuytsia]

I am not sure Galen tried to *kill* Verity? Fitz says he wanted to 'drain him dry'.
I think he wanted to drain his Skill strength to augment his own, and that was his main aim.

Possibly it is easier to intentionally kill with the Skill after the person's Skill strength has been drained to a low level? He may have intended to follow up by killing him.

So, can you Skill-drain a person to death or can't you?........Galen had first attempted to kill Verity by draining him, and would surely not have had much success if draining someone to death were not possible.