I play skyrim with the mod Morrowloot which makes high tier armor and weapons extremely rare; and non craftable. While in a tomb I was fighting a Draugr Overlord and he shouted disarm, taking away my ebony greatsword.

My question is: Is there any way I can get my weapon back?

If it's a stock weapon you can use the console command

player.additem 139af 1

I have used tcl to hunt for misplaced weapons, I really hate being hit by Disarm...

if you get hit with Disarm (I have a lot) I have always been able to find my weapon on the ground. If I am duel wielding, both weapons appear on the ground as one. Picking it up returns it to your inventory.