Diplomacy

Goodwill

Understanding

Mercy

Bitch Be Cool

Actually no, this one.

Stabby
Holy Cardboardia (or along those same lines: Great Cardboardia, Sacra Cardboardia/ Cardboardia Sacra, Mighty Cardboardia, Animus Cardboardium)
Excalicardboard (or Excaliboard) [[Oh whoops, looks like Insane Genius already thought of this one.]]
Corrugated Justice

yes.

Recyclable Rage.

Buster Board.

Flatlander.

Mastercraft.

Masterkraft.

Box-and-a-Half Sword.

Corrugated-no-Tsurugi.

I Am That Isn't.

Undurabil, Blame SHAME of the West. (edited because it's so much better)

Brown Destiny.

Name the sword "Excaliboard", then make a dagger out of papier mache and call it "Papercuts".

Psh. Talk to me when you have a real sword and we'll name that shit up.

These are the best. That is all.

The Boxsword That Holds A Real Sword
+5 Kindling With Quick Ignition and Fast Burning Enchantments

If we're going for Norse?

Ragnabox
Fimblboard
Cardboarjolnir (Even though it's not a hammer).

That's all I got.