[[:case_comitative|Comitative case]] may be confused with [[:case_instrumental|Instrumental case]], as both of them may be translated with English preposition "with". The difference is that either word "together" or presence of companion or emotion is implied in Comitative case, while Instrumental case means "with use of", "using". Compare: "He speaks with fear in his voice" = "Tagashn ufur__sha__ mogtabishi" (COM) vs. "He speaks with flattery" = "Tagashn glizg__irzi__" (INS), "He talks with elves" = "Tashugb golug__sha__" (COM) vs. "He talks with his mouth" = "Tashugb pugtab__irzi__" (INS), "Kill the orc with knife"((order to kill orc that have knife with him)) = "Dog urukum kirm__sha__" (COM) vs. "Kill the orc with (use of) knife"((order to kill orc using the knife)) = "Dog urukum kirm__irzi__" (INS).

The verb "gûk-" (to fill) requires indirect object (if present) to be in Instrumental case: "Fill the barrels with fish" = "Gûk kralt skab__irzi__". But "kralt skab__sha__" means that fish is already in the barrels.