As one of the first bosses you have access to in the game, he's very much beatable by first tier classes.

You just need to plot out your resources properly. Frank has no tricks other than his high HP, so the solution is maximize your damage to him for each of your assaults.

One big thing you might consider is [mid-battle leveling](http://gaming.stackexchange.com/questions/18390/what-is-mid-battle-leveling). In essence, leveling in the middle of a fight to restore health and mana. Of the 1st tier classes, Fighters and Priests do pretty well in your first runs. Fighters get extra experience that makes it easier to setup, while Priests do extra damage to Undead. As it were, Frank is actually easier to face when you're a lower level and can make some level ups.

You can't poison Frank, because of his being Undead, so the main alternatives to keeping his HP low is to rely a lot on spells like BURNDAYRAZ and BYSSEPS to maximize the damage you deal before going to heal. Make every point of Mana count, don't use any exploration or potions that would waste any point of Mana. When you're not relying on potions, you just need to setup a rhythm so that you deal significantly more damage than he does, so that you don't have to punch through it all again as you heal up.

Item luck doesn't really figure in as much. Aside from poison and Frank being undead, almost everything you can find in a shop will benefit you in some fashion.