New Z-rank Item

ITEM NAME: Gram (sword)
TOTAL PAYMENT: 25,000 Jewels

ITEM: Gram
RANK: Z
DESCRIPTION: Gram is a perfect replica created using a special Arc of Embodiment trick. It is a 7 foot long, golden greatsword. The original sword, also named Gram, is THE sword of the Magic Council. It has the destructive potential of the Etherion Cannon which is why it was sealed away with the only key belonging to none other than Bold Reedsprite, the Rune Knight in charge of protecting it. Anyway, what makes Gram so powerful is its ability - the moment that Gram is unsheathed, it has D-rank power. Hold on, it gets better! With every post that Gram is unsheathed, it doubles in power (D to C, C to B, etc~) which gives it the potential of surpassing Z-rank power, given enough time. However, when Gram successfully strikes with power exceeding Z-rank, it forcibly sheathes itself and becomes unusable for a certain duration. Being a perfect replica, Gram (this item) also has this incredible power.
Looks like this - Link
DURATION/COOLDOWN: Until Sheathed/4 posts

Not sure of the "potential to surpass Z-Rank" Ill let Brandish handle this one.

Brandish approved a "potential to surpass Z-rank" here fairytailend.rpg-board.net/t47-kryssa-s-magic
(Hope Kryssa doesn't mind the example...)

Approved.