Would moving 10 of Ghostblade's Armor Pen to its active solve anything?
I mean, 20 flat Armor Pen passively on an item that's already giving high-end AD (the same AD as Infinity Edge for 400 less gold, in fact) plus CDR is a bit excessive. Plus, the active on Ghostblade is meant to be the "go kill someone" button anyway. Why not move some of that flat Armor Pen to the kill button?
I mean, this doesn't do anything to stop Lucian from activating it and Culling you to death with Cleaver, but still. (If you want to curb this, give Black Cleaver a built-in short cooldown for applying its stacks. Long enough so The Culling specifically doesn't stack it instantly, but short enough to not impede basically any other application of the passive. The Tiamat items actually have a short cooldown on their passives so that Shyvana's dragon Q doesn't proc them half a dozen times on a creep wave instantly, so there's precedent for such a mechanic.)
Just my thoughts.