Genie skill Weakness

Kai_Umi - Heavens Tear

I got a few question about it:

What is the actual base atk speed nerf when maxed? (base = without counting stats bonus of genie)

Is it that great?
And if at lvl 10 atk speed is nerfed by 130% like said on ecatomb, how is that even possible?What happend above 100% lol you hit yourself or wut??b:shocked