A large, but a temporary and relatively short-lived AC reduction that immediately times out if you unwield the weapon that inflicted the acid damage—that would be cool.
I like the idea but I have to say that some of the reasoning is entirely off base:
tasonir wrote:currently the viability of short blades is pretty heavily dependant on slaying
On the contrary, there are...
Electrocution, pain, and distortion, the latter two of which have gods who can put them on one weapon permanently, as well as level 5 spells that temporarily put them on any non-branded non-artefact weapon you want. Also berserk, which has an amulet, an artefact property, a potion, and a different god dedicated to it.
Moreover: Stabbing. Which is supported by a major game mechanic (stealth factor) which is linked to one of three stats, and to one universal skill; in addition, stabbing is
further supported by multiple gods, invisibility (available as spell, potion, wand, ring, cloak ego, and artefact property) and most of one entire spell
school (hexes), with further help—albeit to a much lesser extent—from another spell school (summonings) and class of evocables, as allies can allow for distraction stabs; and
furthermore supported by blowguns + paralysis/sleep/confusion needles, which are gifted (and thus supported by) not one, but two different gods.