hi there, incase you're still stuck on it, he's on the bridge just befor the place where the antlion was (that bridge) you'll kill him fairly easy the first time but he jumps off onto a bridge under it and runs away, to find him after that you need to get the site 11 key from the phon coast camp (next to a bujerban man who fell from the sky) go back when you're stronger cos the skeletons and vampyrs in there are loads harder than befor, just befor you get to him again ther'll be a save crystal. advisable to save it cos its very hard.
just so you know i'm level 58 on 4 caracters and 43 on ashe and penelo and i still havent beaten him
good luck to you
Ok first i dont think having people with low levels like that is a good idea,and second give one of your team a long ranged weapon such as Bow,hand bomb,gun...,and do you know that there are items you can only get by stealing from that guy,try checking the faq in this site for FF XII,you'll find out how to get those items from him