I am about to use a Highborn on a Dragon next week against my chaos or High Elf enemy, Usually i put him on a Manicore but i want to try one out.

Here is how i would equip mine,

Highborn - Heavy Armour, Sea Dragon cloak, Blade of Ruin, Enchanted shield and the crown with the 5+ ward and immune to high/light also if points permit i will give him a crossbow.

_mounted on a Dragon.

Out of curiosity, is there a reason you're not using the Gauntlet? Against HE, the Blade of Ruin should be fine, but if there's a chance of being engaged with a T5 Chaos Lord or, even worse, a Greater Daemon of some kind, being S8 would make your character a lot more effective for the points you're spending.

You need to be winning combats when you charge, and by enough to break whatever you're fighting; the Blade probably can't do that, and the Gauntlet can. That's the big difference, in my mind.

The reason why i don't use the gauntlet is I prefer striking strike but using against Chaos i would give him a lance or the Draich of Dark power for the +2 strength and the killing blow ability it is either one of the second.

Also i like to have some form of ward save, also about chaos i am not worried as i found out several times that my chaos oppenent usually uses the berserker sword which in a challege is no use against me.

HA, SDC, Shield, Gauntlet of Power, Wand

When you're using the Gauntlet on a charge, you strike first, same as with any other weapon. If you're charing with a dragon and lord, you expect the target to break from that combat, so you don't get tied up. The gauntlet makes that a lot more likely thean the blade, which leaves you at S4, or the Draich, which still potentially gives heavily armoured units a save.

Of course, when you're designing a list against someone, I suppose that's a bit less of a concern.

yep same as Maedros HA, SDC, GoP. Wand/the 5+ ward save thing for 35pts.
Oh yeah and a shield and a cold one.