Actually.. I almost won the battle the next time I fought it.. it was after I posted the save..
If those mamluks weren't there then I would've won.. I managed to rout those Nubians and kill the archers but after that I didn't had enough men to finish the mamluks..
I'm talking about the second time I tried that battle of course..

I just thought that reloading the save,after Efstathios died, is bad bad bad and I didn't do it..