Have to say that these all strike me as poor changes to make. Going through them one by one:
Rageblade: This item already suffers from a combination of problems that prevent it from being a practical item at most serious levels of play. In order to utilize Rageblade, your champion must: consistently auto-attack (or the AD and AS buff is wasted), have decent or better AP ratios (or the AP is wasted), have medium-short cooldowns, and be able to survive long enough to use the 50% trigger in the first place. The problem is that a champion that meets enough of those criteria is better benefited by Trinity Force (AD, AP, AS, benefits from frequent spell casts) or Blade of the Ruined King (AD, AS, %health damage, sustain that's not dependent on losing health) for AD centric builds, while Nashor's Tooth (AP, AS, extra AP scaling on auto-attacks) and/or Lichbane (AP, massive damage spike from mixing spells and attacks) are superior for AP centric builds.
Your change solves none of this, and adds an abuse case to worry about. Incidentally, a one shot percentage increase plays significantly better with burst, which is counterproductive to the item's purpose of DPS. This should not be implemented.
Nashor's Tooth: So, we're going to remove one of the two items that supports the auto-attacking mage and replace it with a terrible Wit's End knockoff? That's a bad idea. Wit's End does significantly more damage at all stages of the game than this due to the MR drain effect, while simultaneously providing the defense that works best with strong base damages. It's a fighter or tank damage item. Your idea has no defense for the fighter or tank, who will ignore it, and not enough damage to be worth the pickup by a more glass-cannon type. What was the point of this suggestion?
Gunblade: Hard CC should NEVER be placed on an item. Forced displacement, literally the strongest of them? Never stops being a strong enough word. The entire game would then need to be balanced around the fact that every champion can acquire hard CC if they want it. Which is fine if you start from that premise, but League did not. You would need to rebalance/rework all ~120 champions to avoid oppressive chain-CC locks. The rest of your proposed changes to Gunblade are pretty mild, though I do disagree on buffing spellvamp. The spell vamp numbers are low for a reason, because high numbers have historically been balance warping.
New second unique passive: After 7 spellcasts or basic attacks gain a buff called "Rageburst". Rageburst - your next spell or autoattack will deal 10% more damage and you will get healed by 30% from damage dealt.
AP Removed
Now requires only 
to build
Total item price reduced from 2920 to 2570 due to AP removal
Attack speed buffed from 50% to 60%
20% CDR untouched
Unique passive: Basic attack deal 15 + (3*lvl) bonus magic damage on hit
**Lifesteal removed
Spellvamp buffed from 20% to 25%
Now builds from 
Total Price unchanged
Unique Reload removed
Unique active is now a skillshot, deals 15% from target's current hp in magic damage (minimum 100 damage), instead of slow now knockbacks the target by 400 units. Has 50 seconds CD and 700 range.
**
