What you can do is build a little bit of ruby so that you are getting lower to mid teir red chests at a decent rate, then stop building ruby, open only amber (and maybe azure) chests until your amber is high enough for some feet to drop. for repeat amber farming that's not optimal, but if you're just after one set of feet, it is probably better than leveling a new weapon. Having said that, weapon diversity is never a bad thing.
DRG, PLD, BLU, DRK
100+3 Smithing http://ffxi.allakhazam.com/profile.xml?70186
"We are Dragoons, and to make short work of foppish cavalry is our bread and butter."
-Bob Shaftoe, The System of the World