Worn effects
 

I'm interested if there's a way to edit worn effects when it says something like "Unknown DB String 4399-6".

Does this mean it's unable to access that effect? And if so, is there a way to remedy that manually by editing the database somewhere?

i think those are in DBstring.txt file - meaning there is no text entry for that effect in the file
effect may still be actually working (if ist coded), just not shown to the client

Correct, it's because dbstr_us.txt is missing them. Even generating a new strings file against your spell table from Alla's spell editor doesn't fix some of them, I know I have some Vet AA's past the glyphs that show up like this. Wish I had more info for you, but all I can assume is that the effects are from live, and have yet to be coded.. if so, all in good time!

Edit - Here is a topic someone else made about this, and Kayen explains in awesome detail what causes it.

ok great! Thanks a bunch guys.