Hm, I feel like the rocks are picking on us. Nonetheless, I think we can finish him from here. You're still on less accuracy so we might as well take adavantage of your low speed and
Vital Throw~Vital Throw~Vital Throw
Save for getting tripped up by sand tomb you should be able to hit him every time since you always move second. Once again, if you can get him in the water, all the better.