Snarky answer, I use an online conversion site.
So long as a sword is 5 units and your player can lift 200 units then in either case you can still only lift 40 swords carefully! Before we continue, note that m is short for meters, and feet can be shortened to ft.
You can also convert from meters to feet and inches.
It is subdivided into 12 inches.
Especially if going for theatre of the mind, I don't see the problem.
One foot contains 12 inches, and one yard is comprised of three feet.