We had our first siege of goblins but due to the fact my barns were not finished yet, and had holes in their roofs, I did not wish to release the were-lizard. I thought it could get into the Fortress via the holes. Funny, the invaders never tried to do that. So I sent out my squads. Two civilians died and two soldiers but over ten plus goblins died. And they gave me good loot.
Some of which went to the Goblin soldier and some I sold. I had nothing to melt them down with so better to trade them for booze and seeds and cloth.
Wait, what? Why don't you just make the armour yourself? Goblins can use both armour and clothing sized for elves and dwarfs. You can even request the armour to be made in goblin size, if you want. When you order the job at the forge, just press (d)etails, like when specifying what a statue should be made of or should look like, and you will be able to specify the size.
If you wanna go one step further, check the armour the dwarven caravan guards have, see in which part of it the civ symbol is, and what it is. Just imagine, enemy goblins seeing one of their kind ripping them appart while proudly showing off your civ's symbol.
To decorate armour use a craftdwarf workshop. Just link it to the stockpile your armour's at (one trick is to make an armour stockpile set to take from links only, but with no set links. Set a dumping zone inside of it, and just dump and later reclaim what you want to decorate), then a stockpile with the material you want to decorate stuff with.
To be honest, I don't remember if decorating armour worked, but I've seen tons of armour decorated with civ symbols on adv. Mode, so it
should work.