[ExpandNATO]

Iron by itself is hard, but brittle, and weapons made from it can shatter easily, which is not a good thing.

Steel, which is iron mixed with other materials, is just as hard, but is flexible and not so easy to shatter. Problem is getting the mix and pattern right, because poorly made steel weapons have breakage problems as well.

Damascus steel for its time was exceptionally good material to make weapons from and weaponry made from it tended not to break. This may not be remarkable today, but for its time that was amazing.

[monocle]

Pure iron is not brittle. Iron, as it is commonly called, is the product of smelting operations and contains high amounts of carbon which renders the iron brittle although there are two forms, ductile and malleable, of iron which are more ductile. Steel usually has significantly lower amounts carbon. Alloy steels contain significant amounts of metals such as nickel,chromium,etc.

[SoCal Pubbie]

One problem, as I have read it, is that "Damascus steel" was not a common standard, that was replicated exactly from place to place as a modern factory would today. The formulas and methods varied widely, as did the quality of the weapons.

[Kielbasa]

Steel, which is iron mixed with other materials, is just as hard, but is flexible and not so easy to shatter.

Actually, steelmaking is a refinement of ironmaking in which impurities (primarily carbon) are greatly reduced.
(Cast Iron = 2~5% carbon, Steel = 1% carbon or less.)
The controlled addition of alloying elements didn't evolve until much later.

The unique properties of Damascus Steel arise from its forging process, which is essentially a combination of heat treatment & mechanical working that affects the molecular structure of the residual carbon.