User blog comment:Cfp3157/Greek Peltast vs. Inca Bola Thrower/@comment-422690-20151117024446/@comment-422690-20151117164216

It's counter-intuitive, but a metal being harder doesn't necessarily mean it's better. The smelting techniques in use for iron at the time resulted in a fairly high concentration of impurities, which tended to weaken the blade. Furthermore, the predominant forging methods for iron at the time also tends to result in a weapon that's strong either longitudinally or latitudinally, meaning that it's highly brittle if struck the right way. No properly tempered blade will break the first time you use it, but it's far more likely to do so than bronze. Likewise, the only metal that will deform on a first hit is gold; Bronze's higher malleability makes it more likely to than iron, but not by much.

The misconception that iron was better metallurgically rather than economically also tends to stem from modern reproductions using low-quality bronze alloys. Since "bronze" is a rather broadly-defined term, you can have "bronze" that's about 98% copper, which will be very malleable, very soft, and utterly worthless as a weapon material. "modern" bronze is 12% tin and 88% copper, while older bronzes had additional components like zinc, silver, and arsenic which greatly changes the structural properties of the metal. It's easier to generalize iron as being brittle because it's a simple metal, but bronzes are far more varied; some bronzes have the soft, crappy qualities you described, but those aren't the kinds used for weapons.