Iunno if it's supposed to be quite that powerful, but I got similar results when using divine lance on basically anything other than the dragon isles final fight. The skill hits like a bus, which is probably why it has a 5-ish turn cooldown between uses. Also, as far as balance goes, I wouldn't worry about it. Even without going to the debug room and getting cheat weapons, it is braindead easy to make every combat encounter a cakewalk: Just get the growth spurt crystal, stand next to a save point, spam the growth ability to get seeds until you run out of mana, hit the save to refresh your mana, repeat until you have several hundred seeds, go to temple and crank devotion on a party member of your choice, then equip the crystal that gives devoted strike on that party member. Congratulations, you can now deal upwards of 800 damage with your basic attack on every single turn with that party member.