Firstly, go to Fort Memoriam (The place where they re-enact the battles).
Then, enter the mess hall.

If you search the room, you may notice a spittoon.
Search the spittoon.

Dip your hand in there by constantly pressing 1, as the game brutally describes how disgusting the spittoon is.

Click "inventory", select "melee", then select your new weapon, "blechscalibur".

This weapon should do at least 25 stench damage. Now, feel free to crush your enemies with horrible hygiene!