1.8 enchanting seed system exploit

Context
As you know, the 1.8 enchantment system works with seeds only changed when you enchant an item, so that you cannot spam until you get the enchantment you want in the preview box.

Weakness of this system
The problem is that the seed is shared between all the items of the same kind (tools, sword, boots, etc) regardless of the material.

Exploit possible
The enchanting system can be exploited by initializing the seed with a golden item (which has a better enchantability) and then enchant any item of the same kind but made out of another material.

Proof
As a proof I provided two screenshots : it is known that you cannot get any level V enchant on a diamond sword, so it has definitely used the golden sword seed to create a random enchant (here Smite V).