i hate excalibur.damn weapon.holy element is not very useful.ragnarok and brave blade are much better.but they arent legendary,so let's not talk about them.^_^

excalibur is a relatively good choice,though.by the time you get it,it's one of the best weapons you have.usable until the time you have ragnarok and a super brave blade.

though strato has a greater attack power than masamune,masamune is still good,due to its first strike ability as mentioned by shinangel.put strato and masamune together (by 2-swords) for maximum use.

wizard rod always gets into my first 3.strengthens most elements,if not all.useful for black magi,red magi and summoners,especially if you have redx2.

sage staff is also good,if you already have holy.

the two knives,sasuke and assassin,complete my first six.assassin has deathblow (can kill an enemy in one hit) but has lower attack power.sasuke can be equipped by ninjas only (if i remember correctly) but has high attack power.and i definitely use ninjas so sasuke is very useful for me.

i dont really mind the remaining six.it's a case-to-case basis.i take whatever i need.

to sum it up...

first three:excalibur,masamune,wizard rod

second three:sage staff,sasuke,assassin

the rest is up to you.