Strange to post this question on a D&D legacy forum then. Seems like you need a medievel weapons enthusiast forum.
That said, if you have concluded that historians have referred to metal Assyrian clubs as maces, I cannot argue with you.
If you have concluded that clubs and maces are the same definitionally, I will refer you to Dictionary.com:
Mace
a clublike armor-breaking weapon of war, often with a flanged or spiked metal head, used chiefly in the Middle Ages.
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