Korhov has a valid point, your chosen resists use up 19 of the 20 bonus resist points from GM Arms Lore + exceptional quality. If you'd accept horned leather rather than barbed, which gives an extra +2 to fire, the odds would still be pretty sucky but much better than with barbed.
Also, a mempo requires twice as much leather as a regular gorget, so you have to restock your backpack much more often...perhaps you didn't realise how much time & effort would be involved in crafting this item? If you're prepared to be flexible on some of the details, maybe allow one or two resist points less than you ideally would like, then the request will be more appealing