Honestly, they should have just made it similar to the fiery great sword and gave it a bonus damage against the forged since they were powered by Balthazar. That was implied by Kormir and would have caused less of a plot hole. As it stands now, I have pretty much the same question as you.

Gameplay wise GW2 is awesome, but when it comes to the writing, I really don't think Arenanet knows what they are doing or plan anything ahead.