Need more mitigation?

after a reasonable attempt at ulduar 10 (5 bosses) last week, recieved some comments from the healers that the spike dmg compared to the other tank was "crazy" (other was frost DK), at times even to me i went from full to dead within a second or 2.
tried looking at what might have caused it and since did 25-man naxx from which some gear has pushed my expertise to 29 from 20 (without food/flask), only other thing i can see would be my armour levels

Árca - Arathor EU

guess what i'm trying to get at is, are there issues in my gear/glyphs that could be causing the issues? or are the healers possibly not preparing/reacting enough?
(i use SB whenever available and SW when i know large dmg is definately coming)

maybe you could replace the taunt glyph by Glyph of blocking?

Maybe not use Shieldblock whenever it's up?

I use shieldblock: on XT, right after a tantrum, on Ignis, right after flamejets, on counsil when steelbreaker does fusion punch on kologarn I use it when I get 2nd debuff stack.

Gear/gems/spec looks okay for Ulduar 10. I'd be looking at environmental factors related to the encounter that might be leading to me taking more damage (is fusion punch getting dispelled quicky, etc) and at the competence levels of your healing team.

You also might consider blood draining for your weapon.