I'm trying to obtain the guardian skill from the NPC Moose. Unfortunately, when I try to enter the training room to kill the black kentaurus, the dialogue option does not take me into the room. I am wearing a shield, which was required to start the quest. I tried killing normal black kentauruses but it wouldn't work. I might be doing something wrong, but it would be great if Andreas or Kevin could take a look at the script. I wouldn't think this had been reported before considering most people don't care about this skill and not many characters are at this point in progression.
You should be able to complete the quest now. Leaving the thread open since the shield does not get removed correctly if you have it equipped, and you do not lose HP in the map.