Let's Make a Melee and Ranged Fighter

[Darg]

Addressing DR for archers, there's Razorfeather Ammunition (MM V), next to the entry for the Steelwing. Arrows made from a Steelwing's feathers are inherently keen, masterwork, and - most relevantly for our purposes - adamantine. They're also explicitly nonmagical, meaning something like Bless Weapon's automatic crit confirmation will work with them just fine.

Even if you can't get razorfeathers, you can get adamantine arrows (automatically masterwork) for only 61 gp per stack of 20, vs the 1001 gp cost of a stack of 20 razorfeather arrows. Add in an oil of keen edge and you've got an equivalent temporary option for less.