Here are the updates Kamui posted about the Blood Mancer/Zerker weapons:
First, these all scale now, so sample numbers are below.
> Second, the HP cost on these has been adjusted to no longer be based on a % of a 0 END player's max HP, and instead they're now the equivalent MPCost/1.5. We felt that HP costs were a bit low for the benefit that they were giving, so our initial method for HP cost is being ditched and being replaced with this new one.
> Finally, the weapons will now also affect spells/skills of the weapon's element/damage type. Essentially the bonus on these is halved since it's affecting a spell instead of a weapon attack. So you deal +10% damage for the HP cost + MC effect (this doesn't change no matter if the weapon's in Melee/Magic mode, but the spell/skill's damage type/element must match the weapon's regardless), +2.5% damage if wearing a Bloodmage armour, and a further +2.5% if wearing a Bloodmage armour that matches the weapon's element.
As expected, the Tsunami Pen is still better when it comes to spellcasting, since it gets a multiplicative bonus *1.18 instead of additive that will be changed to the latter like Pumpkin Fang whenever it gets updated.