Q 65 Is there a way to get past DR epic/X short of having a force weapon or shadowstrike (don't remember which book it's in) when you're less than 20th level?
A 65: Be a barbarian with a +5 Berserker Blade (Unapproachable East, and a few other sources; OA, i think). It would be a +7 weapon while you rage.
Also, Bane weapons. A +5 Dragonbane sword would function as a +7 sword against dragons.
Oh, and Unapproachable East has the Bladebane spell (Paladin.... 4?) that gives a bladed weapon the bane property for a short while (minute per level maybe?) It has a fairly expensive material component though - a 50 or 500 gp ruby, IIRC.