At Hattin after the Crusaders had retreated to their hilltop last stand positions the knights tried to break through the Muslim lines (either to flee, or to get at Saladin). At least three times. Downhill. And were repulsed every time.

"Arab" cavalry (among whom were many Turkish, Kurdish and Armenian mercenaries) of the period was typically relatively heavy compared to the typical light horse-archer of the Turkic nomads. They typically had composite bows too - although used them in the so-called "Persian" doctrine - but were better mounted on larger and stronger warhorses, and had considerably more armour.
1. At Hattin the Crusader Knight happen to have been in the desert for days without having anything to drink, wearing the heavy Chain Mail, and having endured the fires that Saladin ordered lit which got the infantry to surrender very quickly. The fact is that despite these trials (enough to knock out almost all people today) the Crusader Knights made a great show of themselves at the last stance, true they did get repulsed, however each time the repulse barely happened, and not all knighta failed to charge out, Raymond III and his knights managed to cut through the lines and live to fight another day (Apart from Raymond who according to William of Tyre died "of shame" after the battle).

2. Relatively heavy but again and again European Knights bested them, especially Richard the Lionheart and his army of Britons.

Bedouin or Turkish mercenaries and allies tended to supply the actual light cavalry.

The personal Ghulam formations of all lords and princes naturally had the best war-gear their masters could afford.
True although you would probably be able to tell a Ghulam from a Templar or a Cataphractii.