Why does Black Clever have 20% cooldown?

"Because it needs to be better than the base stats of the items that build it!"

Look:

Athene's Unholy Grail: you are so imbued with a spirit of magical regeneration, that even your spells regenerate faster. 20% cooldown.

Morellonomicon: A tome for magic users, detailing magical regeneration. 20% cooldown.

Nasor's Tooth: A sword, overflowing with magical power. The wielder attacks faster, gains magical power, deal magic damage on hit, and can use skills 20% faster

Frozen Heart: Offering a great mana reserve, and slowing enemy attacks around you. Everything seems slower to the enemy, so you, at the heart of the frozen heart, are able to use skills 20% faster.

Zeke's Herald [which no one buys, so it shouldn't really be on the list]. Your aura inspires everyone to heal and attack better, and you too are inspired to heal and attack better, with 20% cooldown.

Black Clever: A great big axe, working out to use it increases your health, and strength, and you can smash a percentage of enemy armor when you deal physical damage. And you can use skills 20% faster

One of these things is not like the others. . Maybe 2 of them actually with Zekes, but that item just sucks.

I'm just saying: Black Clever would fit in well with 10% cooldown. Items that have 20% cooldown have some lore about them to justify providing 1/2 of the maximum cooldown reduction in one item.