Bless is definitely a weak spell, let alone a source spell; simply because Curse reverts it and many of the late-game enemies either have Curse or bleed cursed surfaces. That said I don't think it's unredeemable, if it simply overrode all surfaces it would be a fine spell.
Which is to say cursed surfaces, instead of going neutral, turn blessed; and curse not being able to affect this particular surface nor having this surface be overridden by other neutral surfaces. It's not that the spell is inherently weak, just that when there are 10 Curse cowboys hipfiring their debuff there is no point to waste precious source on turning necrofire into regular fire.
