4 levels of figther(look at the variants from DR), 5 levels of Wizard(possible specialist/act), 5 levels of Abjurant Champion, 6 levels of Swiftblade!
Now go win D&D!
Your weapon should be a Dwarvencrafted, Razor-Sharp, Oerthblooded, Pureore, Obdurium scimitar. Now just place whatever enchantments you like... I suggest Collision, and Keen!