Staffan said:
The problem with that is that there's no benefit to getting a +1 bow over a masterwork bow - both give +1 to hit.
I'm also in favor of
dropping the MW requirement for weapons. All that does is (a) suck a few hundred GP extra per weapon, armor, or shield, and (b) pinpoint to the PC's exactly which of those items to grab and examine later (if only MW weapons can be magical, then, only MW weapons need be examined for possible magic-weapon status).
House Rule Alert!!
So, IMC, there are three changes I made:
First, the MW bonus is a "masterwork bonus", not an "enhancement bonus". Similarly for the bonus form Adamantine (it's a "material bonus" not an enhancement ...). Thus, it stacks with magic, and/or with Materials.
Secondly, for weapons, the MW bonus can be either +1 to hit (well balanced, or whatnot), or +1 to damage (especially effective cutting/piercing surface(s), etc). For bows, only +1 to hit is allowed; for arrows, either is allowable, but the arrow +1 MW to hit wouldn't stack with the bow's +1MW to hit.
Thirdly, I removed MW status as a prerequisite for magic weapons (etc).
Any old ordinary shortsword could be a Shortsword +1.
So, a
(MW) Serrated Adamantine Longsword +1 would get +3 to hit and +4 damage -- and pre-3.5, would penetrate DR as only a +1 weapon.
After all, if you PAY for each component of a particular build, you shoudl BENEFIT form each, right?
Still, as the alert above says, that's all solidly House Rule country.