What's a Death Scythe in 'Soul Eater?

In 'Soul Eater,' what exactly is a Death Scythe?

Five Death Scythes all together in one spot.

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Death Scythes of DWMA, Wiki

Huge Ass Scythe from SoulEater (Spirit in his Death Scythe form)(unfinished) Minecraft Map

Scythe Death Weapon Showcase : Soul Eater Resonance

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Death Scythe (rank), Soul Eater Wiki

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Soul Eater Resonance of the Soul: Will Soul Eater Become a Death Scythe? (TV Episode 2008) - IMDb

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