People running around in that coat can't have hit the Gae Bolg stat caps then O.o. Only Twin Adder Pieces that are decent are the choker, body, and hat. With the spear, that means dropping stats on a piece to equip dump gear; probably belt or earring. With the 5piece set, at Lieutenant caps, the difference in damage is well...not worth the time gathering the 25k for the weapon, and the ~24k for the other 4 pieces.

At this point in the game, stick with Ifrit > Garuda > Relic; and I wouldn't even spend the gil to gear up on Gae Bolg, since they may be reworking how the stats work. Save the seals, use 'em to rank up and then hoard 'em; assuming they keep the same GC system, the next rank up will be an assssssload of seals lol.