The problem lies in full conversion of the pierce/physical portion of the runes damage. To make a full rune caster you need a way to do so. Although this build uses cold runes to pretty good effect. It also uses a lot of other damage sources. (including jacked up chillwhisper blade spirits)
The energy leech/flat RR was the main draw for me. I’m not sure how much healing it really contributes, but RF with 22% adtch on DW guns is a plenty of healing.
The belt also gives oa, %armor, crit damage, and most importantly +2 inquisitor seal.
Armor is the best defensive stat…soooo
I always build DA to ~2800 on my builds, then dump cunning or spirit for more damage. (unless the defenses are paper thin)