It would be cool right? Dual wieling barbarian merc, that is what barbs do after all.
Sword 1 - Last Wish - provides Might as well as lifetap.
Sword 2 - Azurewrath - Provides sanctuary removing undead bladed buffs and allowing leech.
Last wish is not going to happen, you just wont find the runes in 4 months. But if i had them, i would use this mercenary over A2 merc.
Alternatively:
Sword 1: Grief
Sword 2: Lawbringer.
Sanctuary, decrepefy and killing power. Whats not to like? The merc weilding Lawbringer opens up the offhand for a dualwielding frenzy barb, who could make good use of Beast to counter the lack of might. I would use this over an A2 merc.
Please let them dual wield. No dual wield = no point. Even with battlecry.