The invention relates to a blade of a rotor of a ninth phase of a compressor, which can be defined by coordinates of a discreet combination of points, in a Cartesian reference system (X, Y, Z), wherein the axis (Z) is a radial axis intersecting the central axis of the compressor, the blade having a profile which can be identified by having a series of closed intersection curves between the profile itself and planes (X, Y) lying at distances (Z) from the central axis, the blade also comprising a thickening, substantially parallel to a base portion of the blade itself, fixable to said rotor, said thickening being substantially situated half-way up the blade and being suitable for shifting the natural resonance frequencies of the blade itself outside a functioning frequency range of said rotor.