Blackmog, Jebus is trying to point out that, the way armor pen is calculated is: armor-flat-%
so with a flat armor pen of 50, and last whisper, vs a 100 armor enemy -> 100 - 50=50 - 40% = 30

so youre wasting gold on armor pen, with last whisper only you would end up vs 60 armor, while having space for more damage :)

I clearly stated ignite was useful and that summoner spells dont really matter
The ghost blade is a very last resort thing so we wont worry about that armor pen
And besides, cant have too much armor pen :)

Heal is an incredibly mediocre summoner spell. Search it up on any forum - they will all discourage you from using it. Ghost, Flash, and Cleanse are all so much more useful.

You've also got way too much armor penetration. Your Ghostblade combined with your runes nets you 45 flat armor penetration already, meaning that Last Whisper is losing out on so much potential. A flat AD item like I-Edge would serve you much better.