I do atm got both swords on my warrior and to test things out I dual-wielded them and kept hiting a targetdummy, doing the normal fury-rotation. As fa as I can see the sanctuary buffs DO NOT STACK. If Glaming procced first, then burnished it just overwrited it like if you got a higher level buff of anything else. Gleaming never procced when I has the sanctuary buff from Burnished up. The internal cooldowns did not seem to share as Burnished could sometimes proc 1-2 seconds after Burnished.
So for DK's that want to duel-wield them. Yeah you will get a higher uptime on the sanctuary buff, but they will never stack so that way it is not that imba. I would suggest dual-wielding it together with one of the ToC weapons instead =)

