Maybe the holy fire that burned him became somehow a part of him and the scars are some physical manifestation. Kinda reaching here cause I had the same question you did.
I think the asssssin noticed Barbatos and/or at least heard her convo about being in contact with Zagan; so no, she wasn't accused because she was saved by a sorceror.
Just to be clear both names are supposed to be read as Amamiya, Yoshi, the guy translating the WN, just spelled the names differently to make a distinction for us English readers.
What nonsense are you saying; being around Van, the object of their worship and their desire to be useful to him is what has healed them of their trauma.
can you imagine this behaviour occurring in the time of honour and chivalry among nobles. could see several duels occurring from this level of disrespect and probably a full scale war just from this level of disrespect