Same thoughts at first, i was kinda sad when i saw the dmg number. BUT...if u noticed that it can strike the same enemy twice, futhermore it has AoE dmg.
It even applies flames of devotion twice on the same enemy and it can crit twice, but that in return means it can also miss twice.
Not sure if this is in fact intended or not. I am also not quite sure if the dmg numbers in the battle log add up, because the dmg number popping up over the heads of the enemy aren´t close.
All in all i am not sure if it´s way overpowered or weaker than a normal great sword.