Grim Reaper

[Raimun]

Become a Bone Knight (PrC from the book "Five Nations").

You'll get proficiency with all Martial weapons and you can craft an insane skull armor with immunities and a scythe that harms the living more and it can be made Magical too. Leans towards the undead. You'll only lose one caster level but it has some weird requirments like Craft and Ride.

Also, you can be a Cleric of a cause (check the Cleric's entry from PHB). Just pick two Domains, like Death and something else. Say that you are a Cleric of Death. Ask if your DM would let you pick the War Domain and have it apply to scythes.

Edit: Both options can totally be Neutral.