Im not sure, but I always assumed that it meant, that the damage bypasses the AC-based calculations, and is instead applied based on the target's cold-resist?
It means that if you pass the resist check it will act as 1 normal damage added onto the weapons damage, if you fail the resist check you get nothing (per hit checked)
Raw +dmg will yield better results than +cold/fire damage due to that extra resist check. There are a few augs around that add + fire/cold/etc that are typically easier to get than +raw damage for non-raiders, RSS springs to mind.
From recent parsing I have done at level 85 (Max on my TLP). I had one weapon with 90dmg +3 Corruption Dmg. I compared max hits from this weapon to a straight 90dmg weapon. Here is what I found. (The numbers are made up but close) 90 damage alone -- 1000 Dmg Max hit... so then I equipped the 90+3 dmg weapon. 90+0 ---- 1000 90+1 ---- 1015 90+2 ---- 1030 90+3 ---- 1045 Adding up all the "Max Hits" and dividing them by the total hits, gave me an average hit over a LONG parse of 1015. This means that my Avg Hit uses 1/3 of the Elemental Damage. Thus, I only include 1/3 of the dmg into my considerations for weapons. So while it should not be discounted, it should not be considered a 1:1 exchange of dmg. a +2 dmg aug will do more average damage than a +5 elemental dmg augment.
90 raw weapon damage doing 1000 mob damage is 11.1 mob dmg to weapon dmg ratio. 1 corruption weapon damage doing 15 additional damage is actually better than the raw damage. I know you spit-balled the numbers from memory, but it threw me off.
Yeah I was using easy numbers, it was more like 1188, 1201 etc. But using 1000 and then +15 was cleaner to math off the cuff. Reality is that I believe my calc dmg ratio was 12.53 which made some increases 13 and others 12, but i didnt want to overly confuse the issue.