Your levels are ok. You need more skills, though, since you don't have certain ones such as Haste and Dispel. If your armor isn't upgraded, then upgrade it. Also, do you have Bubble? Bubble doubles your max HP, and this can help out. If your clan rank is high enough, then you can buy this spell from the Muthru Bazaar.

Anyway, this is what you should do:

1) Leave the area and buy the Dispel and Haste spell. Dispel'ing a boss's buffs will be a big help. This will be important in later battles as well (e.g. esp. when more and more foes have Bravery on). A foe with Bravery status can hit for a bit more damage than he would otherwise, so it's really important to dispel that.
2) While you're gone, go to Balfonheim Port and upgrade your armor/weapons to the best kind available.
3) Buy any other current spells from Balfonheim as well. Blizzaga will be especially useful for this battle because Tyrant is weak against ice.

If you are in need of gil to get the stuff you need, you can chain mirrorknights in the western section (Walk of Dancing Shadow) of the Feywood. Keep chaining them until you get 99 Windslicer Pinions. After that, go and sell all the loot. You should get 150000-200000 gil.

Having the Mage's Monograph will help you get more and better drops from them. It shows up as the Forgotten Grimoire in the Bazaar, which sells for 21000 gil. To make it available you have to talk to any magick merchant over 25 times.

If you want to do some leveling as well, go to the southern part of the Golmore Jungle (above a Feywood entrance). Equip everybody with Embroidered Tippets (doubles EXP points). Kill all the foes there. After you do this, skeletons will starts spawning. Start chaining them. You can do this until level 50. Each skeleton gives about 930 EXP w/o the ET on.

When you get back to try to take on the Tyrant again:
The very first thing to do at the beginning is Dispel. The important things to keep on are Protect and Haste. For your healing gambits, set everyone to use Curaja if HP gets less than 60%. Have Esuna or Remedy gambits ready to deal w/ Sap and any other ailments. Since you can't use technicks, use Ethers instead of Charge to help replenish some Mana if MP < 10%. You can have a person cast cast Blizzaga on Tyrant since he's weak against ice.