The story
From ham (“thigh and buttock of an animal slaughtered for meat”) + fisted (adjective), probably referring to someone being clumsy as if they have hams at the end of their arms instead of hands.
Etymology from Wiktionary, CC BY-SA 4.0.
ham-fisted
ham-fist·edToday it means: Lacking skill in physical movement with the hands; clumsy. Full definition →