Leonardo used twin Ninja-Tou, steel swords of usually inferior make to samurai swords, roughly sharpened and straight bladed, coming to a slanted edge point (as in \) instead of a curving blade that came to a fine point.
(His weapons were mislabeled on his toy information and his card and have been called Katana ever since).
Donatello wielded a bo, a staff made of tapered hard wood (e.g. bamboo or white oak).
Raphael wielded two sai (both singular and plural), dagger-shaped truncheons with two curved prongs (yoku) projecting from the handle. Used to fight sword users and disarm them as well as for stabbing.
Michelangelo fought with twin nunchaku: two sticks connected at the end with a steel chain.
Used as a blunt instrument striking weapon like clubs but with more force due to rotation.