CD Reduction - to help you spam your Spells in early game.
Atack Speed - to help you to last hit better in early game.
Armor - to help you to tank Minions better in early game.
Armore Penetration - Good for your 'E', Kayle does not really need Magic Penetration or Ability Power -> 'R' does not scale with it, 'W' does not require Magic Penetration.

I know that the normal Masteries look like this: 21/0/9 or 0/21/9 or something else, but Kayle is a very special Champ and therefor needs special Masteries. 26 in Offense to, obviously, max. your own Damage-output. Because Kayle is only focused rarely in Teamfights (because she is not a Carry) she doesn't need any defense Masteries, Runes or Items and even if, you still got your 'R'. I skilled Wandere because it is helpfull to reach Teammates in danger faster with it.
--->I do not claim the rightto call this the perfect Masterie Skill Tree for Kyle!!! I am using it and everything is working very fine!!! Nothing Else!!!<---

Dagger as first item to make it more easy for you to last-hit. If you don't like Mikael's buy Athene's instead (I don't like it because it gives you to much CD Reduction [20%+10%+15%=45% Max.40%]. Fiendish Codex and Stinger instead of Guinsoo's because they give early CD Reduction and other cool stuff for less money. Trinity Force next, to advoid having no room for Phage and Sheen so you have to wait an enternity till you have enough gold to buy it in one piece.

Righteous Fury is your main Spell. It allows you to farm fast and efficient, while harassing your enemy with it's AOE. Reckogning will also alow you to harass your enemy and the slow will annoy your enemy, also it will make it hard for him to last-hit without being hit by your 'E', also don't be afraid to turn around, when you are chased, and cast the you 'Q' on your follower to slow him down. Divine Blessing is essential if you want to play solo top. use it to escape, to chase and to save your allies from being killed. Intervention should only be used on yourself when you are in big trouble. Normaly you should give it to dyeing Teammates or Carrys in a Teamfigth to allow them to max. their Damage-output.