Archi swings pretty hard, but you shouldn't be taking that much damage per hit if he is fully debuffed and you're using armor potions. Since threat isn't an issue in this fight and your dps warriors can get knocked out of range via airburst, focus on keeping the debuffs up yourself.
We got our first kill last week and he was hitting me for ~5.5k a swing.
Also, I found avoidance trinkets to be far superior to stamina in this encounter. EH theory assumes a steady income of heals, which you may not get on this fight. Also, proactively use your cooldowns on fears, since that's when your healers will be interrupted and will have to scramble to catch you back up.
/also, look at the badge cloak and new badge ring for this fight...the extra armor helps reduce his swings.