I'm not sure if you can say that there is a 'standard word' for objects in Polish. 'Dwie sztuki' (two pieces) and 'dwie rzeczy' (two things) would fit this phrase, but 'dwa przedmioty' (two objects) wouldn't.
It actually needs the fit the thing you are referring to, that's why we accept all possible genders in this exercise.
So if in the given context you had referred to the things to be taken using a feminine noun, you would say 'Weź dwie'; if using a masculine or neuter noun,'Weź dwa'. And if no particular noun was salient in the context, you could choose arbitrarily between 'dwie' and 'dwa'. (?)