DarkKnight: Dark Impale Skillbook/SP question.

I have a few small question regarding dark impale.
I saw that every SP used in Achilles would be put in dark impale.
Does that mean that Achilles books will turn into Dark Impale books?
Or is it a skill that you would have to learn through a book?
And is the skill Lv 30 right away?

Thanks in advance~

Achilles shouldn't be changed to Dark Impale books. Pallys keep Achilles, so it is still a needed skillbook.

Oh yeah thats true, i forgot about that. So ehm any chance you might know it works with if you need to learn it or need mastery books?