Sharpening Stones and Rusty Weapons (not working)
 

I attempted putting a sharpening stone into a forge with a rusty 2hander yesterday and it kept telling me "those items do not combine" (not the exact wording, but close).

I tried with 1 single sharpening stone and the sword, and then 2 non-stacked sharpening stones, 3, 4, etc... same results.

This was at the main forge in Grobb. I didn't test this at another forge.

PS Really enjoying my time so far. I dunno how long I'll last, but it's been a blast seeing the old sites. Thanks for all the hard work!

Most recipes won't work using the container itself. The new menu-based tradeskill UI is the only thing that is guaranteed to work.

I believe this was the issue. I had no trouble with this combine.. then I noticed you were using, I assume, the Troll forge.

pending update:
Added 'troll forge' as a container choice for creating Tarnished Weapons

As Nilbog pointed out you may have been using a Racial forge. Thankfully you didn't lose any of your material.