A shedding mechanism on a Jacquard-type weaving loom, this mechanism comprising at least one movable hook, moved by a knife according to a longitudinal direction (X100, X200, X300), between a bottom dead center position and a top dead center position, in or near which the hook can be retained by a selection device which comprises at least - an electromagnet that includes a ferromagnetic core defining at least one first pole face and at least one second pole face, these pole faces being offset from each other according to the longitudinal direction. - a retaining lever configured to retain the movable hook when it is in or near its top dead center position, the retaining lever being mounted with the possibility of pivoting between a position remote from the electromagnet and a position in contact with the electromagnet, about an oscillation axis fixed relative to the electromagnet in the operating configuration of the mechanism, the retaining lever comprising • a ferromagnetic armature that interacts magnetically with the first and second pole faces (S122, S124) to control the angular position of the retaining lever about the oscillation axis, this armature comprising an outer attracting surface that faces the second pole face when the retaining lever is in a position in which it is in contact with the electromagnet • a non-magnetic body integral with the armature characterized in that the non-magnetic body of the retaining lever comprises at least one abutment surface, which is - adjacent to the outer attracting surface - away from the electromagnet when the retaining lever is in its position remote from the electromagnet; and - in contact with the electromagnet when the retaining lever is in its position in contact with the electromagnet, and in that, when the retaining lever is in its position in contact with the electromagnet, the outer attracting surface is away from the second pole face. - an electromagnet that includes a ferromagnetic core defining at least one first pole face and at least one second pole face, these pole faces being offset from each other according to the longitudinal direction. - a retaining lever configured to retain the movable hook when it is in or near its top dead center position, the retaining lever being mounted with the possibility of pivoting between a position remote from the electromagnet and a position in contact with the electromagnet, about an oscillation axis fixed relative to the electromagnet in the operating configuration of the mechanism, the retaining lever comprising • a ferromagnetic armature that interacts magnetically with the first and second pole faces (S122, S124) to control the angular position of the retaining lever about the oscillation axis, this armature comprising an outer attracting surface that faces the second pole face when the retaining lever is in a position in which it is in contact with the electromagnet • a non-magnetic body integral with the armature characterized in that the non-magnetic body of the retaining lever comprises at least one abutment surface, which is • a ferromagnetic armature that interacts magnetically with the first and second pole faces (S122, S124) to control the angular position of the retaining lever about the oscillation axis, this armature comprising an outer attracting surface that faces the second pole face when the retaining lever is in a position in which it is in contact with the electromagnet • a non-magnetic body integral with the armature characterized in that the non-magnetic body of the retaining lever comprises at least one abutment surface, which is - adjacent to the outer attracting surface - away from the electromagnet when the retaining lever is in its position remote from the electromagnet; and - in contact with the electromagnet when the retaining lever is in its position in contact with the electromagnet,