A character using an improvised weapon in lieu of their signature weapon

Captain America using a car door instead of his shield. It even has the signature star in the middle

Kratos using a bridge that's shaped like a sword instead of his blades of chaos (This might be cheating a bit since it's just a regular weapon with extra steps)

Ursa from the new Predator movie using a piece of scrap as a shield

Tony Stark using a bunch of improvised weapons like chemical grenades and a homemade pistol instead of his suit

In the Telltale Walking Dead spinoff game, Michonne is separated from her katana and instead uses a machete for the duration of the story. She still fights with the same techniques she normally would with her katana.

I love this trope because it's a fantastic way to reinforce a character's fighting style while giving them a chance to be crafty about it. As a fan of the media, you INSTANTLY understand a character's still fighting at full capacity even without the special sauce that's usually with their signature weapon (IE, the vibranium in cap's shield, the high end tech on Tony's suit, etc.)

Every single time I see it happen, I just get tingles in my brain.