Rageblade and Wits End anti-synergy

Champs who typically build Rageblade usually found Wits End a good buy too, especially the hybrid magical autoattackers like Kayle/Kog/Varus. Old rageblade used to be a synergy buy, because it gave more damage with more ap, which further scaled up with the MR reduction of Wits End. Now that it no longer gives more damage but % penetration instead, it actually anti-synergizes with Wits End because of the penetration/reduction priorities:

% Reduce > Flat Reduce > % Pen > Flat Pen.

Since Wits End reduction is applied first, it now makes Rageblade's % penetration smaller, which was not a very big number to begin with. Perhaps make it a slightly smaller amount of % Reduction instead (smaller amount because % reduction is stronger than % pen) or make it stack like BC (which fits the theme of rageblade users autoattacking a lot) while keeping the non-stacking with void/lw?

Personally, I like the idea of just moving the hybrid pen passive on to guinsoo's rage (gain X% reduction per stack until the 6th stack)