Why this is quite viable!~
Even though in the masteries there are no points in the defensive tree.You will hold your place in the top lane very well. Due to the flat armor in the runes. you may also test Scaling armor but i prefer flat armor seals!.The reason to no points in the defensive tree is because for extra sustain i took the defense points and invested them in the utility for the extra 3% life steal. it may not seem like much at first. but your life steal quints are 6% too. If you add that up thats already a whopping 9% lifesteal at spawn! In the addition theres the doran's blade passive that is an extra 5 hit points on hit, and then there is your w. this will give us a load of sustain to survive the laning phase and destroy the enemy!
Why Blade of the ruined king?(Botrk)
I had chosen botrk for some reasons... it provides a large amount of utility. Such as the life steal, attack speed and although i might not seem for much the attack damage. in addition botrk's passive and active skill are very very useful indeed. That extra 5% of the enemy's hp per hit helps us do a ton of damage earlier on and later on in the lane AND in team fight scenarios. now lets think about botrk's active. It takes 15% of your target's hp and hands it over to us which is helpful although, that isnt all. it STEALS the targets move ment speed 30% to be precise and gives it to you. Since Aatrox doesnt have an escape except his jump and flash it will help alot against champions such as Jax,wukong and Jarvan IV(J4). They all have annoying skills that trap you like wukongs ulti or jarvans ult and jax's counter strike( E ). Botrk has all these perks which makes it a Glorious choice for Aatrox and some other champions and adcs!