Highest buffed weapon damage can be achieved thusly:
Make an Orc (+10% weapon damage), legendary weapon damage enchants on every piece of v16 jewelry, a full agility set for the aforementioned jewelry, two legendary Molag Kena pieces, two legendary maelstrom swords, a full hundings rage set (way of air at v14 would give more weap/spell damage but you'd lose out on v16 enchants so nope), a major brutality buff (best one by far is rally), minor brutality buff (like from grim focus) - am I missing anything?
That's how you get all those ridiculous numbers, like the one dissolved up there. Just a matter of buffing and stacking galore.