If you equip an umbrella, use the "spin", and quickly switch to another weapon, you will be able to attack with the weapon you equipped, but still spin with the umbrella. Even if you drop or trade the umbrella, you will be able to make it spin and deflect bullets.

This works until you unequip the umbrella and equip a new weapon, or if you traded/dropped it, until you equip something to the empty slot.

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