yes, a gargoyle obtain a 10% extra weight + 8% for any item burned in a soul forge, but I'm not sure about the right percentage...
I tried with the dread pirate hat:
base weight: 392
gargoyle bonus: 431
with queen forge: 465
Elf/humans need 452 base weight for obtain a relic.
You can get only 1 relic fragment per item (maybe a weight of 1000 will give more, but is impossible to reach

)