Yeah, under stiffer rules. Technically speaking his class is an adventurer, like Yunyun said, but that's not really a class at all, more like a job. I'd say he's rogue because he prefers no to little armor, ranged combat or sneaky close combat. An assassin is very close to a rogue, and the drain spell would fit nicely there. Create water is useful for anyone, except for a sugar man, and freeze is a basic attack skill with some versatily (like freezing a floor and causing enemies to slip). So, by the process of elimination, that would be it, at least. Other classes would fit even less. His behavior certainly fits as well...