This French M1866 Chassepot Cadet/Childs bayonet is indeed a rare piece. Besides being around only 2/3rds the size of the normal M1866 Chassepot bayonet it also does not have the tightening screw at the top of the muzzle ring.
The Cadet/Childs bayonet was manufactured by Andreux of Paris as stamped to the ricasso. This bayonet has obviously seen a lot of wear but remains in good condition without damage, however, the scabbard does have several dents. Serial number to the crossguard is 76(94) whilst the scabbard shows number 688 (889). (Reference WW No.194 and JN 69/3).