Do you actually have to steal the hammer ? I didn't tryh it, but would guess that if you steal anything from Raphaël's house (like the giant strength gloves) and try to leave, you'll have to fight him.
I am not sure if stealing items from the
hidden stoarge room, like Mol's (or your's) contract from triggers him but...
.. You can steal the gloves of strength ond amulet of health without any need of fighting Raphael
if done correctly, Raphael fight is triggered from when only Orphic Hammer is stolen, that is to say I just don't know about the spoilers if that is included as well.
Correct way that works is casting a darkness spell on the artifact and going invisible, all the while enemies red cones for indicating their visuals also stays far away from you during thats process and you have to be very quick about disarming the trap but never tried the Indiana Jones style.
