Hilgigars' Siren Flute

[PuPu]

Ok, so the Fairy Flute is a rather powerful weapon for Eiko for that point in the game (since you just got her). You don't have another chance to get it for a disc and a half. This is probably the only hard steal that is worth doing.

By that time, Eiko most likely has better weapons. In fact, the only things Eiko's weapons are good for are abilities. But fine, if you think Esuna, Haste, and Regen are so important that you absolutely must get it before Oeilvert, fine.

Demon's Mail: You don't have the resources or time to get it on disc 2. You can get it in several places rather shortly after the Tanitarian fight, and you don't really even need it until you fight Ozma. And it only gives the High Tide ability, meh.

You can find one on Mount Gulug. That's almost as long as waiting to get Fairy Flute in Oeilvert. You can also get it at Daguerreo for 59000 gil. Is stealing it from Tantarion longer than getting 59000 gil?

Holy Lance, Orichalcon, Grand Armor: By this point in the game, you have access to the Master Thief ability, which makes these no longer difficult to steal. You can get the Holy Lance from a moogle not long after you fight Ark. You can get Orichalcon in Daguerreo shortly your chance to steal it. And you can synthesize a Grand Armor before the fight with Nova Dragon.

The next place you get Holy Lance is Terra. Again, that's almost as long as waiting for Demon Mail or Fairy Flute. And Kain's Lance isn't until Memoria. You said that the Fairy Flute was worth stealing because it was a good weapon. 3rd best Lance in the game isn't good enough?

The Orichalcon, fine. It's not that important to steal if you don't mind spending 17000 gil.

Yes, you can synthesize Grand Armor before Nova Dragon. However, the only problem is, if you didn't save a Mythril sword from Disc 1 all the way until Disc 4, there is no other way to get it other than Nova Dragon.