I love tinkering with odd builds! This one looks fun.
I think that you’ll have to choose between BWC or Sigil, due to points. My preference is sigil, mostly due to the fact that I dislike how BWC feels. sigil is easy, casts faster, and has the healing component that is lifesaver at higher levels.
GEAR:
Pants - I’d go with boneweave leggings. May seem odd initially, but disregarding the vit damage (which isn’t bad since you are doing some already), you have the skill + to sigil, and it casts it’s own sigil (which can stack with yours). I love these pants, the sigil is a lifesaver when you have those pesky raged mobs that are hanging back and pinging you while your stuck in the main group. Alternative is pretty great pants/tranquil mind, or Green for stats.
Boots- Golemborn is always good. Greaves of ill omen seems odd, but has vit damage, and solid resists on top of it. Greens are probably best for stats/resists.
Gloves - Voidsteel. Nothing else really compares. It’s got your damage type, attack/cast speed, much needed resists, skill bonuses for you…not sure what else would top it.
Shield- Aegis defender all the way. + allskills, and fire damage to boot. Nice Phys resists as well.
Devotions look fine, typical fire/chaos build. An alternative would be to go into order as well. You’d lose some top end damage, but gain a ton of defense.
Here’s a setup with no BWC. it allowed me to boost sigil allot, and add in flashbang as well as blast shield, 2 important demo defensive’s. The devotion tree is only an alternative, could still be tweaked a bit, but much more defensive, and takes advantage of your shield in the devotions.
http://www.grimtools.com/calc/4NOQyBaV