How long and heavy would a bronze sword have been compared to an iron/steel sword? Would Valyrian Steel swords seem absurdly long to First Men warriors, or would they look more or less the same as what they were used to?

From what I’ve learned from a quick bit of research, the whole iron vs. bronze thing isn’t about hardness or weight or anything like that. Rather, if you can forge iron, it’s way more plentiful and doesn’t require access to both tin and copper. The ancient bronze world relied heavily on trade networks to get access to both, so if disrupted bronze cultures would have a hard time replenishing their weaponry whereas iron cultures wouldn’t. 

I would imagine this meant that when a bronze-using army encountered an iron-using industry, the issue is that the iron-using army could equip itself more cheaply and easily, so could afford to equip more soldiers than the bronze army could for the same amount resources.