User blog comment:B214/General Discussion/@comment-207.96.205.3-20170320002607/@comment-10330822-20170320003948

Possibly, but I feel Crom would never rely on anything but his own strength. So him using a treasure to make himself stronger seems unlikely. It's probably just all training, most dragons don't both getting stronger, and Albion and Ddraig just got stronger for each other, Crom on the other hand has just been training no stop, for the day he could face his great opponent. My guess is that the enemy he's been waiting for will be Issei.

Still, the mythology behind Crom Cruach is very vague about what he could do. His name is the Crescent Circle Dragon. But his name's translation can roughly mean "bloody crooked one" or "bloody crescent". So crescent is in his name. So the secret is probably behind the circle in his name. His magic hasn't been shown yet, he's shown no special powers other than raw strength. I find it hard to believe he's all brawn, Dragons at his level at least have some kind of abilities. As to where he gets them, he probably just naturally developed them like every other dragon.