What does Two-Bit's switchblade symbolize in The Outsiders?

Two-Bit’s switchblade symbolizes the greasers' toughness and loyalty, as well as how violence has become woven into the gang’s identity.

Two-Bit carries the knife as part of the greasers’ world, where being ready to fight is treated as normal. When Bob and the other Socs confront Ponyboy, Johnny, Two-Bit, Cherry, and Marcia near the blue Mustang, Two-Bit pulls out his switchblade while giving Ponyboy a broken bottle. The knife shows how quickly the conflict between Socs and greasers can move from insults to real danger.

The switchblade also symbolizes loyalty. When Dally is in the hospital and desperate to join the rumble, he asks for Two-Bit’s prized switchblade. Two-Bit gives it to him without asking questions. That moment shows how greasers protect and back each other even when they know trouble may follow. Dally later uses the switchblade to force his way out of the hospital, and then threatens the doctor with it when he fears he will be kept from seeing Johnny.

For Two-Bit himself, the switchblade connects to his place in the group. Ponyboy thinks before the rumble, “Soda fought for fun, Steve for hatred, Darry for pride, and Two-Bit for conformity.” Two-Bit’s knife it is a part of that conformity: it's part of the overall image of a greaser that tells outsiders he's associated with the gang.

The knife is different from Johnny’s switchblade, which is tied more directly to fear and self-defense after Johnny is brutally beaten by Socs. Two-Bit’s switchblade is more of a social marker that signals loyalty, image, and group identity. Its movement from Two-Bit to Dally also shows how the greasers’ devotion to one another can be honorable while still keeping them trapped in violence.