Haldir notices somebody huge sits behind him by the absolute enormus shadow casted in front of him, and he turns around thinking he’ll see a giant and he instead sees a minotaur, and this is where he stands up, about to grab his sword or dagger (you said he carries it) and then Alcibiades says his “Oh not again, if you’re gonna slay me than do it already, just not another exile” or the “Don’t hurt me please” and Haldir realises he’s not likely to attack anybody in there because he looks like a monster even though he’s not one and they both sit down and during the lecture they’re talking about their age, the one thing they found to have in common
Ok then Haldir is surprised then reaches for a pocket knife (as he obviously doesn’t want the teachers to know about his sword, because he doesn’t care if they know he has a knife is a sword that matters to him)