How much did one of those ancient battle swords weigh ?
Probably not as much as one might think. I'm not an expert, but I have been reading up on the development of the sword. For the medieval age, a viking sword would've been about two or two and a half pounds, and even a big two-handed norman longsword would've only tipped the scale at between three and four pounds. Maybe six for a really big one. The big German GrosseMesser (big knife) was only about four pounds and it was a fairly imposing chunk of steel.
I don't know for sure about all pre-BC era swords, and I haven't studied the Macedonians/Greeks/Romans yet, but I'd be suprised if they weren't similar. The Roman gladius was quite short and light and fast.
Movies like to show big, heavy (10-15lb) monster swords like Conan's but most weren't like that. In actual combat a sword like that would have been slow and cumbersome. A soldier needs something that he could swing repeatedly without exhaustion, and something that would be quick and nimble to handle.
I've done some exercises with a 2.5 lb viking sword... and it's quite a workout. It's the speed that makes the thing. It would challenge anyone to swing one through a series of cuts for more than 15 minutes before your arm feels like its gonna fall off.
Sword weight... I just saw this, and should have checked before replying, in case the question has been answered. Sword weight varied; bronze swords tended to be massive and short, because they were more of a chopping weapon than a thrusting weapon. One old story involves a Spartan warrior who complained that his sword was too short. His mother upbraided him with the reply, “take a step forward, then it will be long enough.” Iron (and later steel) swords were longer and narrower, and were more versatile and effective.
The spears used (for example) by hoplites were thrusting weapons, but on occasion were used in a more club-like fashion. Javelins were thrown weapons. Alex’s dad Philip innovated a number of things, most significantly with his infantry (spear length was increased, with rear rows keeping theirs raised to protect the formation from projectiles, and front five rows straight ahead) and with the introduction of “belly shooters” and integrated cavalry. Alexander grew up in all that, which is probably one of the reasons he was such a success.