when i tried strengthening a rusty sword, it turned into an op magic sword

It sounds like you’re describing a magical or fantasy scenario where attempting to strengthen a rusty sword unexpectedly transformed it into an overpowered (OP) magic sword. This kind of event is common in fantasy stories, games, or literature where objects can be enchanted or gain extraordinary powers through specific actions. If you’re asking when this kind of thing typically happens, it’s usually during a key moment in a narrative — perhaps when a character tries to improve their gear and accidentally triggers a hidden enchantment or a latent magical property in the sword. Could you share more context? Are you talking about a specific story, game, or a creative idea you want to develop? That would help me give a more precise answer!