User blog comment:B214/Question & Answers 5/@comment-71.120.219.7-20150903234625/@comment-1359322-20150904040507

In my own word and terms (for Irregular).

Subspecies = different form to suit wielder's taste/preference. E.g. Blade Blacksmith original Balance Breaker creates an army wielding Holy Weapons, subspecies Kiba, Dragon Knights with Holy attributes, Jeanne, Dragon made of Holy Swords.

Irregular = something out of the norm, different than the normal standard. Like the Sword Birth being able to produce Holy Demonic Sword when Sword Birth by normal can only produce Demonic Swords.