Akkadian malku = king.
Akkadian shalatu = to rule.
Akkadian malku is used very rarely for the Babylonian or Assyrian king; usually it designates a foreign king. It is in any event not the main word for “king” in Akkadian.
The root š-l-ṭ does mean “to rule”, but there is no word for “king” from this root in Akkadian. Actually, in Arabic sulṭān is primarily an abstract noun “rule, dominion” and only later does it take on the meaning “ruler, king”.
Akkadian šarru seems related to Hebrew s-r-r (with "sin", so an Arabic cognate is expected to be sh-r-r).Do we know the original meaning of the root for shar?