User blog comment:Jopjopjop/Volume 18 Spoilers/@comment-3965848-20150511212720/@comment-16281343-20150512055550

@Gary [Boost] is not a Naruto-Kurama kind of thing where Ddraig gives Issei power.

It's just that; it doubles the power of the user. That's why even with Boosted Gear, Issei was considered weak because he himself is weak. Even if he doubles his power, it still amounts to nothing. Ddraig didn't gave him anything.

Boost, Transfer, and Penetrate are all Ddraig's ability. Same with Divide, Steal, and Reflect with Divine Dividing.