Tool Of Thief, Toy Of Queen. Always Used To Be Unseen

Answer: A mask. Why each line points to a mask: Tool of thief: Masks help conceal identity, a classic tool for thieves who don’t want to be recognized. Toy of queen: Masks are used in masquerade balls and royal pageantry; a “toy” here suggests ceremonial or playful use by nobility. Always used to be unseen: A mask hides what’s underneath—the face—so it’s “used to be unseen” by design. Sign of joy, sign of sorrow: Theater masks symbolize emotions (comedy and tragedy), making them visual signs of joy and sorrow. Giving all likeness borrowed: Wearing a mask lets you “borrow” another appearance or persona, replacing your own likeness with a new one. Source: https://riddles.com/408