ok, can't tink of any answers atm so just gonna try to translate each line and see if theyre correct

Great I am, and --> probably something large, or with a lot of power
one of a kind, but --> obviously it's unique. in gam,e terms this would probably mean it has it's own model
don't get too carried away now! --> probably telling you not to underestimate it, unless of course this is a punn? or if it is something you can possess then don't overestimate it.

heaven doesn't grant you --> would indicate that whatever it is has some association with heaven and divinity in some way. or possibly coming down from above
all that you seek. --> i kind of know what i want to say here but can't find the words like it would leave you unfulfilled, or there is something it is missing
no! for riches and power you have to work hard. --> if this line is to be translated literally then it is obvious what it means. working for riches makes me think of the mimics in omega dungeon, or the gillionaire ability.
By the way...
doesn't it remind you of seafood or shellfish???? --> again, this is obvious if it is meant to be translated literally

i'm gonna guess Godhand, just because it is a celestial weapon (heaven) and gives money (gillionaire) and power (it is a CW after all)