Plus side is if your using only one weapon, you can put far more enchantments on it for the same price of 2 weapons getting enchanted. Use that to your advantage and stack the damage buffs, shock, flame, frost, acid, sonic and do +5d6 rainbow damage a hit. If your one handed weapon is something like a morning star and does multiple types of damage, your set for life on that part at least. The only real concern is optimizing it via feats/class features.

Power attack, cleave, great cleave come to mind. There was also a feat on the srd (in the supplement/other companies area) for feats - there was something like Flay or something, you do +2d6 damage to enemies with full/above max hit points (temp hp counts). With this combo in mind, cleave and great cleave with a decked out one handed becomes pretty potent in the start of a fight.