A walī does not claim prophethood; the walī affirms and follows the Messenger. A muʿjizah validates prophethood, while a karāmah makes no rival prophetic claim.
The shared feature of extraordinariness therefore does not erase the different evidential functions. The accompanying claim remains essential.
The unusual gift of a follower is understood in harmony with the truth of the Messenger followed, not as evidence of an independent new revelation.