Minecraft arrows on hand?

I recently wondered what it takes to put arrows on the left hand (mine) in Minecraft. Does anyone know what the purpose is? I look forward to your answers.

Actually none because it is actually intended for shields or swords etc.

Sorry, but what kind of question is that? I mean then you could also ask what it takes to put andesite in the other hand. And to your question, no it's no use.