Formulae is not in the game yet, so it is not used.
To make 100% weapons, you need an R7 smith. Ranking your forge allows for items to be made faster. There are some people who say that an R7 Forge will allow better items to be rolled. While there is probably no proof, you will roll items faster, thus getting more items, thus the chance of better items.

Higher rank Vendors roll higher quality items.
Certain racial Vendors roll certain items more than other Vendors.
Higher Rank forges allow items to be rolled faster.

LIMBO
Morbid - 61 Prelate
Brim - 55 Mage Bard
ApacheSBX - 48 Barb Thrower

CATACLYSM
Jumpin 'Jehosaphat - 42 Centaur Prelate

TEST
Kenai-X - 73 Centaur Prelate
*dash is messed up
Kenai-X - 59 Centaur Barb
*dash is ok