U have some rly good points in that. I might consider changing it a bit... But to be honest the role of a glass cannon has rly worked to me. But Yi is easily beatable as u say. Thank you rly much about the feedback!!!

Getting life-steal early on is a bad idea. Unless you defend bottom (?), you will find that the amount of HP from the scepter is inadequate. You gain at most 15 HP per hit (assuming you hit 100, which is an overestimation in itself). Good players use exhaust on Master Yi and focus him. And if you are not focused, you don't heal because you have more or less full HP.

Going 21-0-9 is better (only magic damage comes from Alpha Strike and Bloodrazor (if you ever get it). The EXP and Utility Mastery helps much more than the cooldown reduction and penetration (your ultimate makes the CDR a bit useless).

Finally, do not go glass cannon. It doesn't matter if you are a carry: you do more damage alive than dead. It'd be bad to buy only defensive items, but going only offensive will encourage losses in ranked games.

Not voting...yet.