Hand it to a summoned ogre? Enlarge a fighter cohort and have them swing it.
My dm just gave this to my group. No one in the party wanted it since it was large and had the negative for size. I took it because I figured I'd find a use for it. Yeah, yeah, I know. I'm a wizard. However, the weapon itself wouldn't sell for much (maybe 8k...maybe).
I already have a lot of magical equipment, so I also figure I should make use of that +3 enhancement bonus.
What are your guys' thoughts?
You (or your party) couldn't use it anyway. As a large 2-handed weapon, it is simply to big for a medium creature to use. Just sell it and put the money toward something you can use. The 9000 gp you would get is enough to buy a +2 weapon you can use, or almost enough to buy an upgrade for an existing +2 weapon to a +3 weapon.
I went to the trouble of looking up the Monstrous Physique and Giant Form spells before I noticed you said Conjurer, not Transmuter.
Go ahead and summon something stupid and muscular. It will appreciate the club.
Animate dead? large sized creatures that can use a weapon are fairly easy to find most of the time, just hand it to a bloody troll skeleton, and use it as a beatstick
Trollbone can summon a troll to beat things. Animate dead is probably best though, being permanent.