Weapon Null Argument Exception

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The description for Wahai Poraga pollaxe I just found in the Undercroft reads:
 

System.ArgumentNullException: Argument cannot be null

Parameter name: key

 

Then it has its actual flavor text. Also the tooltip doesn't appear for this weapon.

 

I'm on the latest mainstream patch, and I verified the game data through Steam.

 

I can provide the information listed on the stickied post, but file attachment size is currently limited to 0.5MB; too small for savefile of 2 MB.

I will provide screenshot and savefile through whatever means is requested.