User blog comment:B214/Volume 17 spoilers./@comment-72.174.16.60-20140611074407/@comment-75.71.33.79-20140612000017

I think the focus is too much on "Power" v "Ability":

"This is just my hypothesis, but maybe the God from the Bible didn’t get rid of the Two Heavenly Dragons powers completely" - Issei 17.1

I read that as referring to the powers/abilities that are currently missing. So God from the Bible did not destroy or omit the missing powers/abilities, but instead sealed them away to be recovered under certain conditions.

Perhaps I'm wrong about this, but if that is the correct interpretation then the question of "Does the Jugernaut drive use the power of the Dragon or the potential of the host?" becomes easy.

It uses the available powers of both host and dragon.:

"“If you find out about how you can hold back on your strength, then you will be able to fight right away while having Ddraig support you. By gaining experience and also by strengthening yourself by training every day, it will certainly become easier for you to tune your powers when the time comes. I won’t say something like asking you to control Sekiryuutei’s power all by yourself after coming this far. You can only prove yourself when you team up with Ddraig. But you also need to learn how to distribute your own power since it will put more burdens on Ddraig if you don’t. That’s why I gave you this training, you know?” -  First-Gen Sun Wukong 17.1

bSo their powers/abilities/output is a combination of both. One making up for the weaknesses and adding to the strengths of the other.