No script needed! Just add a RACE=11 tag in the DFN-entry for your weapon, and it will do double damage against all creatures that belong to Race #11 (as defined in DFNDATA/RACE/races.dfn). Conveniently, all undead creatures should already be setup as members of Race #11
I now have a list of about 84,000 items, which include a combination of all DMG/DURABILITY/ACCURACY/SILVER weapons.... Where would be the best place to post this file for others use?