Resist Normal Weapons only checks ammunition for ranged weapons
Weapon quality and/or enchantments does not allow to bypass normal weapons resistance if used with normal ammunition. Custom enchanted normal ammunition works fine. Tested on dremora lords and scamps with various weapons and ammunition. The Unofficial Wiki states that weapon enchantments should count: http://en.uesp.net/wiki/Morrowind:Resist_Normal_Weapons
I'm using the 0.43.0 version of OpenMW.
(RM-4384 from redmine: created on 2018-04-09 by tmt_01 ., )