right, I'm back with comments from our lore keeper.
-=oOo=-
Surgery:
"Damian prepared a tea with Chamomile and Volarian... The man fell asleep soon after the drink was given to him."
This combination of herbs makes a great treatment for Insomnia and Anxiety. The herb lore is specific in this regard because it is /not/ an anesthetic. The sort of unconscious state necessary for surgery is not achievable with this combination.
The sort of state that is necessary to operate on someone is only achievable with our lore with Irid Cap (which you may want to double check your spelling of as you have it as 'iris cap'). It would have to be drank but the potency necessary for this has just as good a chance to kill the patient and takes a practiced hand to make. If he is to be surgeon he will need to know how to do this before hand or else it breaks realism not for it to kill people. This is the nature of anesthetics as to this day they still cause death in patients when miscalculated or even when administered correctly.
"Damian started to sew the skin of the man’s leg back up as he had practiced so many times on corpses at the Lyceum."
technically he needs to reattach the muscles if the leg is ever going to do anything with it again. Just as a small note for future reference.
"When the man woke up he was endlessly grateful and was willing to explain the situation to Damian"
The man would be in excruciating pain and would physical therapy for months to follow, and that's assuming the novice surgeon got all the bone fragments out. (If not he'd be in pain for the rest of his life) for a peasant with no access to medicine as the backstory explains this is a huge issue for him. so I wonder when he'd of woken up and at what point he'd be able to convey anything.
Poison:
"Damian grabbed a powder out of his satchel, mixed the powder into a glass of water from his father’s bedside table, and gave it to his father."
Damian is trained specifically as a healer. The followers of Isohel don't seem the type to train in poisons what-so-ever, so it doesn't seem likely he would know of how to make poisons. We also have no lore for poisons like this, and it causes issues with perms and OPness to allow one that just causes a horrible death right away.
The simplest solution for this is to add that he obtained a poison from somewhere in his travels back to his home kingdom, and modify it's effect to take a few days. You've got the ground work to allow for it, I hope this isn't too much of a problem to correct.
If you want him to know how to make poisons then it's a different animal all together and a much harder problem to solve. PM Staff with questions if this is the route you want to take, sadly this one may take a while as it involves releasing a new lore.
-=oOo=-
So those are the stuff. Now, my suggestion is that, since most of the problems come from the medical lore conflict stuff, make the medical details rather vague. I do appreciate your efforts to study our lore and add details pertaining to it, but really, I can't expect you to be overly familiar with all of our lores.
So say for example, the leg surgery bit. Remove the bits about chamomile and the irid caps, and simply say that Damien handled it with his superior medical knowledge, and because he was able to handle it so well, his mentor was impressed. As for the poison bit, you can follow our lore keeper's suggestion and say he happened upon the poison in his travels, as it would be odd for a healer to carry about poison. Maybe he stopped some traveler from mistakingly ingesting it?
If you fancy the challenge, however, feel free to, well, read up and mess about. If not, well, make the edits and bump the thread.