Clan Titan

What does this skill do exactly? I bought one and have yet to see the option for it.

it prevents you from being mesmerized. It will automatically go off.

It will kick in if you use normal attack against an enemy that uses one of the special attacks; backstab, berzerk, ieutsu and mesmerize. If succesful, the monsters special attack will be negated and only a normal attack will be seen. Sage is the only foolproof protection against mesmerization that the game offers, however you will very easily run low on the skill since all the mentioned special attacks will deplete your uses. Using the sage skill is an all or nothing decition. You either choose to train all sage (+1 trader + 3 fighter for the bonusses to gambling and waking up events) or you completely ignore it and tries to knock out the monster before it tries to mesmerize you.