Would it be possible to add a way to edit the Proficiency of weapons?
Just use Whetstone after enabling unlimited use items.
If it is the same without a trainer, and red aura enemies 1-hit kill, then it may indicated a scripted death. Trainers usually don't stop scripted events from happening.
It wasn't a scripted event.
I edited my previous post to state that it was because my level was back down to 1 when I started the game again and forgot to edit my stats. Once I did that, the same enemy did not one-hit kill me.