This spell should be modified as Keen Edge was to work on non-slashing weapons.
Definitely.
This would be extremely easy to do.
I don't know about the balance concerns, though.
It is like a very high level Greater Magic Weapon, that only lasts rounds instead of turns. I'm not sure if any PC in EFU:A has gotten it though. I'm doubtful of that -- unless it's on an item.
It's been on items, but a PC has never had it as a spell.
It's usually given as loot for some PCs. I'll change it next time I got the mod because that was the point of the loot!