Did you check the guide? I don't remember if you find another one at the end of the game or not. Check to make sure. Control-F if you have to.

after the meeting with the princess in the corridor outside of the Yilsid entrance you remove the purple gate and enter you should fight two yilsids and then a priest, the priest has the fourth Akba rock and the fifth is in the chest in the room where the little beast and little troll are kept. Hope this helps Oh yeah if you enter the yilsid entrance and fight the two guards you will hear a priest yell out and go into hiding ... at this point you will never find the Fourth akbah rock and will have to restart the game...

the 5th Akbaa stone is on the priest's inventory, who stands at the entrance of the ylsidy bunker as josephthediviner above statess.That priest spawns thought only if you have forged&enchanted the meteor sword.I know its 2 years late but you know other might have the same problem.