Well, to be an Enchanted Item, the Scythe will need to grant some kind of magic...call it Ritual (Ectomancy) allowing you to effect ghosts in various ways, that'd make sense...
Okay here's a build:
Scythe of Death:
Item of Power [+2] effecting;
Ritual (Ectomancy) [-2]
Refinement (Extra Item Slots) [-2]
True Strike (As the Sword of the Cross power of the same name) [-1]
Total: -3 Refresh.
Enchanted Item:
Mordite Scythe Blade (Weapon: 10 attack with Weapons, thirteen times per session) [12 Item Slots]
Like a Warden's Sword, it was made by someone else. In this case someone with Superb Lore (you'll need to run this idea by your GM to get it accepted). Or have Superb Lore yourself, of course (you could do worse than Superb Lore and Weapons for the character listed).
Aside from the Scythe, I'd take Inhuman Speed [-2], Inhuman Recovery [-2], Inhuman Toughness [-2], Living Dead [-1] and a Catch worth at least +1 (I have no idea what Catch such a character would have). That should make you good to go.