The damage this weapon will do to a mob is 7 which is the same as a diamond sword.
Here's a video that shows you how the Sword of the Zephyr works: http://www.youtube.com/watch?v=XyQSdQDKWuM
"You have merged the elemental fury of a wand of lightning with a thaumium sword.
When used to strike a foe, the blade will sweep in a wide arc, hitting additional foes near your main target.
While blocking, the sword will conjure a sphere of whirling winds around you, pushing enemies and loose objects away and deflecting incoming projectiles."
|Sword of the Zephyr|
To craft Sword of the Zephyr place a thaumium sword above a wand of lightning on an Infusion Altar. Then place 16 Aura, 8 Fractus, 8 Motus and 16 Telum, in your crucible. This recipe will consume 100 vis from your wand.
If you right click on a golem (or maybe some other things, but not everything seems to work), and then exit out of the GUI, the sword will repel entities as if you were still blocking indefinitely, but you can still attack and move at normal speed. Note that this does not prevent fall damage. This effect stops if you block again or equip something else.