A possible way to solve the Rageblade problem
Why not just split the item in 2 seperate items, here's how it would work.
Guinsoo's Blade (image used just as an example)
+25 Attack Damage +25% Attack Speed +25 Ability Power
UNIQUE Passive: Basic attack grants a stack, at 6 stacks gain Guinsoo's Rage. Guinsoo's Rage: Gain +48% Attack Speed, +24% Bonus Attack Damage, and +24% Ability Power for 5 seconds (duration refreshed upon basic attacking).
Build Path:
1000g + 
875g + 
435g + 590g = Total 2900g
Blade of Fury
+40 Attack Damage +40% Attack Speed +40 Ability Power +10% Cooldown Reduction
Passive: Basic attacks deal 5 (+10% Bonus Attack Damage) physical and 5 (+10% Ability Power) magic damage on hit. UNIQUE Passive: Every basic attack triggers on-hit effects twice.
Build Path:
1300g + 
850g + 
1100g + 50g = Total 3300g
Leave your thoughts on this in the comments bellow.