I mentioned this in a bug report, but i would like to see people's reactions.
When you place a stack of throwing items (i used holy throwing axes) into the deconstructer, it does not even let you get that far, just giving you a warning that you cannot deconstruct that. I can sort of understand that, since the throwers would be much much cheeper to deconstruct then an actual battle axe of the same thing.
HOWEVER, when you toss a returning throwing item (+4 throwing dagger of returning) (or is it +4 returning throwing dagger, cant remember atm) it DOES let you put the item into the deconstructor.... however it dose NOT let you actually DO anything with it.
That means that you cannot deconstruct returning items, you cant remove the +, you cant remove the returning tag, or anything else it seems. It would also seem to be that you will not be able to ADD returning to an item.
Personally, i think that we need to allow crafting of returning throwing items. Currently, there are VERY few of some types while tons of others (how many returning throwing stars have you seen lately in chests/end rewards that were not named). I would LOVE to add banishing on a throwing star/dagger or some other useful effect, since curently if you want a good throwing weapon, you need to green steel one.