Why do i always feel weakness in my hands after making a fist? why do my hands feel that way?

Some thoughts: If you make the fist in response to strong emotion, not unique afterwards to feel a let-down or "weakness". If you have a pinched nerve at the wrist or within the central palm, such as carpal tunnel syndrome, the fisting action could create further compression and more symptoms. Could be sorted out with an emg/nerve conduction test if necessary, if the problem intensifies.