The only 'arab' army faced by the crusaders was that of the Fatamids of Egypt and even their army was 'arab' in name only. The majority of the soldiers were Sudanese, Trukish or Berber slave-soldiers know as ghulams or mamluks. The arabs were an minority of the regular army and supplied mostly heavy cavalry. In addition the Bedouins supplied and effective force of auxliliary ligth cavalry.
The Fatamid army was inferior to that of the crusaders and suffered repeated defeats at the hands of much smaller crusader armies starting with the battle of Ascalon in 1099. Unlike the Turkish armies to the north the Fatamid cavarly were not horse archers but mailed lancers similar to the crusader knights albeit somewhat less heavily armoured. Though not lacking in courage the Fatamid cavalry never learned how to match or defeat the impact of the charging crusader knights. In hand to hand comabt the fatmids were simply outmatched. The fatamid cavalry was also unable to break the crusader infantry which was much better equiped than any they had faced before, thsi allowed the crusader infantry to support and protect the knights succersfully setting the stage for the decivise charge by the knights
The infantry was unarmored spearmen and archers of mixed quality, the sudanese archers the best of the untis and were famed for their accuracy with the bow and their willingness to fight in close comabt with mace and sword. But they were too often deployed in exposed positions with insuffcient support by other infantry of cavalry which led to them being overrun by the charging knigths.
The armies of the Seljuq/Saljuq turks to the north in Syria and Antolia was an entirely diffrent matter which I'll deal with in my next post.