It is a lot but important because of his q.

You don't need attack spd boots after you read below

The cooldown of Steel Tempest is unaffected by cooldown reduction and is instead reduced by 1% for every 1.72% of his bonus attack speed. This is capped at 66% cooldown reduction with 114% bonus attack speed.
At max rank, the minimum cooldown is 1.33 seconds (1.4 attack speed). Yasuo's 4% attack speed per level is factored into Steel Tempest's cooldown reduction and cast time reduction. At level 18, Yasuo has a total of 68% bonus attack speed from leveling alone.
Since it caps at 114... take 114-68= 46% now with masteries getting 5% and the static shiv getting you 40% it leave you with 1% from max cd.

For his crit chance, he needs 50% total to be at 100. So with the shiv being 20 and the Infinity edge being 25 you need to make up 5% to be at 100 percent chance.

Going with runes after meeting these two requirments you face mid lane champs so you need the mr, the armor for mid game because you wont get armor items until late game, and lastly armor pen since you don't have any pen.

IF you want to build differently I suggest don't getting anymore than a shiv for attack spd, and 45% total crit. You are a squishy champ so mr for mid laner in runes, boots to keep it going. Armor for late game when teams break off, health because if you're any good they will start to focus you. OH and of course dmg cuz you love hitting 700+ dmg every swing.