Item abilities are attached to the item, and when the item is removed (via throwing) the abilities no longer exist, and are removed.
Yes ... that should be quite obvious.
Except ...
Its just as when you swap a Shortbow for different one ... you also just removed your item, and yet your bars remains perfectly fine ...
Or if you swap your a Shortbow for a Longbow ... sure, new ability will be added, but old ones (atack and Hamsting Shot) sit still on place where you put them ...
And while the weapon is bound, there is no returning you throw the item away AND YOU HAVE IT immediately back in your hand.
So CLEARLY ... the engine is capable of doing that.
Its all just matter of some kind of condition like "if bound > then skip this part of script > else do it" or i dunno, im no programer.