Is it showing lvl 26 or lvl * (star).
It should be lvl * in order to use any catalyst.

as i mentioned earlier, atb recharge is v simple when u fighting army troop in eden hall (so u can forget about axis blade & just opt for lion heart instead). plus when u get the speed sash & still have many other accessories will help u to recharge the ATB. when u grow stronger & having 10K HP or more, u might not need to summon edilons also. just cast magic, rav & com will do. 
as for fang u shud opt for taming pole for stagger lock option, below is the explanation.
Stagger Lock
    "Prevents staggering of enemies"
          Not as bad as it sounds, since other characters can still stagger
          the enemy and the character can still raise the chain gauge.

Quick Stagger
    "Allows instant staggering of enemies near their stagger threshold."
          Allows characters to stagger enemies quicker than usual.

Below is the weapon recommendations

Lightning: Lionheart (for Commando)
            Axis Blade (for Ravager)

      Sazh: Vega 42s (multiple roles)
            Rigels (for Commando)

      Snow: Paladin (he's best as a Sentinel anyway)

      Hope: Hawkeye

  Vanille: Healer's Staff (for Medic)
            Belladonna Wand (for Saboteur)

      Fang: Taming Spear
For mision map guide please refer to the link below (which i find the best site so far)

http://twobrothersandasister.com/?p=6455

just click on the map to enlarge..

http://twobrothersandasister.com/wp-conten.../mission/55.jpg

for mission 55,

Good luck.

One rant from me.

WHY CAN'T WE CAST ULTIMA...