The weapon crafter is in a small house near Gongaga on the World Map:
http://guidesarchive.ign.com/guides/2301/images/seller.jpgFor the Goldberries, they inflict Slow-Numb + Resist which means you need to Dispel the Resist off first then use a Soft; but the attack also ignores status-defence so if you go in with protection against petrify/resist those statuses can become 'locked' onto the character when they're forced on so avoid equipping Jem Rings, etc.
Chef's Curse prevents the use of Restorative at the start of the battle, but you can get around it either by using a different element to heal (i.e absorb fire, use fire magic to heal the party) or by entering the battle with some party members KO'd and then reviving them (I think someone mentioned that this works).
When a Goldberry moves right or left, they gain Reflect or Peerless respectively. When they move forward, either effect will be removed from them (you can also remove it using Debarrier but this has a chance to trigger a Golden Grudge counter attack). And about Golden Grudge, there's 5 different types; #1 inflicts damage equal to the number of escapes the party has made + inflicts Poison, Confusion, Mini, Dual, and Death Sentence. #2 inflicts 4/32 of your current HP as damage and applies Reflect. #3 does nothing, except it makes the party member grow in size as little. #4 deals damage equal to 1/2 of the target's MaxHP. And #5 deals damage equal to 3/4 of the target's current HP.
Fastest way to beat them is with a powerful Magic nuke combined with Quadra Magic, like Bahamut ZERO though you might need to open up with Debarrier+All first to make sure it hits all of them. They only have 52,000 HP each so if you can get this combo off and survive the wave of counter-attacks then you'll be in a good position to wrap up the fight.