Toggle Non-Lethal Attacks option on. (from character spellbook under Common)

The issue with non-lethal attacks in EA was that it had no story implications, the NPC would eventually disappear from the game same as if they were killed.
The only benefit was for RP purposes and to avoid breaking your Oath as a Paladin.

Things might have changed since then. I am curious to see if Minthara resurfaces as well, might prompt me to restart my playthrough.