Fortified Brass, Seventh Legion. Elude, Vigor, caltrops, dual weild skill one (the life stealing stabs), flex slot, possibly reapers mark for the debuff. Cp in physical damage and pen. One two two weapon damage glyphs. Throw Bone Shield on second bar in case there are enemies about and 1h/ Shield ultimate. Critical Mundus.
Or just buy imperial physique and run around with insane stats and 30k hp in medium.
In all fairness magicka can farm these bosses far better, i usually do it on my magblade.
Sometimes on my stamplar, its all about knowing boss mechanics and keeping your vigor up.
I run a DW/Bow stamblade exclusively - gear is important for these bosses but I actually think the key for this is skill choice - obviously you need multiple sustained heals, and no gear will offset a poor rotation in a prolonged fight. For sustained heals in these extreme cases, I run Blood Craze and Rend, and Vigor is up constantly, and of course the trick is to keep up sufficient sustain.
By the way, Blood Craze appears to stack, at least to a point - I am on console, so I can't test thoroughly. If anyone has quantitative info on this, I'd be very interested in seeing it.