Copper isn't really that bad of a material. It's heavy, so it's good for some things. Any armour is better than none. And if you have silver (which you do) then you can make quite an effective military out of just those two materials.
Good:
Copper or silver bolts. (best of breed)
Copper or silver hammers. (best of breed)
Copper shields. (good for bashing but heavy)
Average:
Copper picks (they'll remove more limbs and pierce more brains/organs than you'd think)
Copper spears (anti-big-thing weapon. Clowns basically)
Wooden shields (just as blockable but lighter than copper, and slightly flammable)
Bad:
Copper armour (heavy, crappy, but way better than just clothes/cloaks. Get a high armour user skill and you'll be fine).
With a decent sized, well trained military with just these weapons, you probably can take on the HFS successfully. You'll definately be able to combat the goblins without too much trouble. And then use the lovely iron they bring for better weapons/armour (or make it into steel if there's any flux at all. There's often marble down at the lower z-levels). ANY addy you can get your hands on is worthwhile. Even 5 addy axes and 5 addy spears will up your kill ratio a stupid amount. Don't worry about the armour, clowns will rip apart dwarves sometimes anyway, and one fully armoured dwarf is 10 or so weapons worth of candy. Just make weapons.
Try dwarves with: 1 copper crossbow, copper bolts, copper pick, copper shield, full armour. Swap the pick for a spear or a silver hammer for different squads. 5x3 dwarf squads (2 of spears, 2 of picks, 1 of hammers) will repel most seiges once they've run through your traps. In fact, give every non-military dwarf(barring miners/woodcutters) you can a crossbow, a wooden shield and a pick/spear/hammer. It's makes it pretty scary for things to invade a fort when you've got off duty militia everywhere. Then arm every dwarf in your fortress like this, armour them as you can and invade hell.
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