Blade is a lot easier:
_**KEEP**_ this item as a marksman item, no melee buffs and ranged nerfs to it, just revert the attack speed and attack damage back to 40% and 25 respectively to keep it as a pure basic attacking item. The extra AD and less AS is what made the item bought on everyone so just revert this change and keep it **_PURELY_** for the basic attackers, which are traditional marksmen. This will solve the vast majourity of balance issues you are having.
Get rid of the on-hit reduction since it messes up with the balance of the game (there are way more fucking on-hits than just Blade of the Ruined King, the fact that this has to be said just makes it whoever came up with the on-hit reduction passive a complete retard).
The balance of Ninja Tabi stems from a further issue and is not about nerfing Ninja Tabi, it is about having waaaaay too much attack damage you can get from the game and from the items (even Long Sword is too gold efficient the fact that you can get 3 pots with it and have more AD than Doran's Blade, more sustain and damage in the early game, should be at least 400g for Long Sword), especially the fully completed AD items are giving so much AD that you can pretty much get as much AD as AP now and that doesn't even include AD ratios being higher than AP ratios and AD increasing the damage on your attacks (hurr durr, its called ATTACK DAMAGE).
Should Ninja Tabi get a true nerf? Yes, and do not give it a nerf-buff / buff-nerf with the on-hit reduction [just fix Blade, the only outlier, instead of throwing the entire game out of whack with nerfing all of the other on-hit items and on-hit champions], just a true nerf BUT Ninja Tabi nerf has to also be placed with a nerf to the overall attack damage you can get in the game and this will also make the traditional marksmen shine better for tank busting with their sustain damage since the caster marksmen no longer over do their damage, same goes for AD assassins (all the assassins have balance issues since its impossible to balance high burst damage champions with high mobility, either they get mobility or damage, but cannot get both in order to be balance-able for the game [work for Ubisoft and make Assassin's Creed if you want a highly mobile character that one-shots, this is fine in this case since it is player vs AI]).
~ Blade of the Ruined King revert the AD/AS back to 25/40% from 40/25% so its focus is on basic attackers and not (literally) everyone
~ Ninja Tabi forget the on-hit damage reduction completely and just solve Blade's problem directly and place it in its proper position as an item for (ranged) basic attackers to kill the tank line and not double up on anything
~ Ninja Tabi will need a nerf, but only when you nerf the overall AD in the game AT THE SAME TIME otherwise AD champions will have a field day since they are getting way too much AD right now (nerf the AD on the completed AD items).
~ Nerf Long Sword's gold cost to be less gold efficient and not out perform Doran's Blade in the early game.