Can you roleplay using a weapon as a tool, even if you cant equip it?
Weapons as tools
Sure. There's no magical forcefield that prevents you from using weapons or tools that you aren't proficient in. Roleplay away!
To clarify, it's all right to use a greataxe or spear to dig a hole very poorly... but it isn't to use the magic light hammer that gives +20 Lore without having the knowledge to properly equip it.