Don't know why the problem. Until The Powers That Be can investigate further, are you just looking to get the sword? If so, use the command
CLUAConsole:CreateItem("UNDSLAY")
to get it.
Thanks but that only partially helped. I was able to create the sword but then it was unusable.

Here's a screenshot of my Vindicator; you can see where the Death Reapers swords are flagged 'unusable'.
http://www.firish.com/BG/BGoops.jpg