Looted weapons come in a variety of types that are randomly assigned. The base weapons are standard: long, short, broad sword, claymore, dagger and falchion, some more exotic base types may drop but I haven't seen any. The modifiers for the weapon can appear in two places before the base name and one after so could have three modifiers in total. I had for example an Iron Mailed longsword of Stone. Some prefix modifiers are : Crystal Steel, Silverweave, gold, platinum, copper, tin; variously encrusted types include opal. amethyst, diamond, emerald, viz "opal encrusted longsword"; this list is not exhaustive. The inline modifiers were like mailed, reinforced, heavy, light, ruined, scorched, bones. The postfix modifiers were typically "of" something, the ways, the leader, enlightenment, the serpent.
If you stick to this kind of formula I think you will be okay to name any weapon you wish just so long as it does not give great power. Some of the modifiers have detectable effects others were possibly unimplemented or gave an effect that was impossible to work out. I think the biggest effect was 20 points to a base stat however some affected more than one stat. As far as I know only looted swords and daggers and a few axes have had this kind of modifier applied to it but that doesn't mean they are all that could. In some ways you are better off inventing bludgeoning weapon modifiers because you will not ascribe the wrong effect to the given modifier.
