peter:
Iron is far more common than bronze (copper+tin),
but nowhere near as hard. Steel can be made as hard
as bronze, but that wouldn't help Hannibal much because
his army wasn't very big to start with. Carthage,
rich as it was, could probably afford to arm them
all with bronze weapons anyways.
What hurt the romans is when the goths and persians
got steel, because they had massive populations which
couldn't all be armed wi/bronze but could be w/steel.
In addition to that, the low cost of steel made it
possible for the goths to use it for tools to work
the difficult but fertile soils of northern europe,
their population boomed and within a few generations
they had a horde of steel-armed people looking for
new lands...
Meanwhile the persians made heavily armored cavalry,
using far more metal than would have been affordable
with bronze. These cavalry were covered with steel
from their head to the horse's knees, and were referred
to as 'cataphracts'. They were later known in europe
as 'knights', and roman swordsmen just couldn't cope
with them. That's why the byzantine army was later
composed of pikemen, crossbowmen, various ranged support,
and of course their own cataphracts.
Way to go with the discovery btw. Benoit:
Carth always was ahead technologically, but were too few
and too friendly to go conquering the world with it.
That's why I think they should have a -20% age cost bonus.