I think you misunderstand how Aptitude weapons work. What they do is the following: whatever weapon-specific feats you may have, you can apply their effects to the Aptitude-enchanted weapon.
Lightning Maces is specific for light maces, so if you have two Kukris with the Aptitude enchantment, you can use them and still get the same effect as if you were using light maces.
With Improved Critical etc., that's a lot of extra attacks, which can be crits again and so on. Blood in the Water helps to get obscene damage output. The only thing I don't like about that build is the fact that it relies on crits. So many things are immune!