All white con weapons are roughly the same DPS ( damage per second ) as each other.
A pair of dual weild weapons are roughly the same as a two handed weapon. One handed weapons are roughly the same DAMAGE as a two handed, but are roughly 25% slower.
Bonuses on weapons vary, but when looking at the raw DPS, it's based on the weapon type. Anything white, yellow or orange is good. Blue is getting old and should be replaced. Grey.. if you're a fighter with a grey weapon, you suck. Go buy a store-bought weapon.
Weapons have teirs, based on skill. You get 5 skill points per level, roughly 1 per mini-level (2 bubs)
First Teir 1-50
Second Teir 50-100
Third Teir 150-200
etc.
Once a weapon turns white, the next teir weapon of that same time turns orange at the same time. At that level, both weapons are equal, though the the orange weapon will continue to grow in power, while the older weapon will never get any better.