Regeneration in D&D 3.5 is pretty weird on its own, but a discussion with some friends today made me realize that, as far as I can tell, alignment subtypes allow a creature to bypass damage reduction, but not regeneration.
The wording used in aligned regeneration states that being wounded by an aligned weapon. For example, the pit fiend's regeneration:
A pit fiend takes normal damage from good-aligned silvered weapons, and from spells or effects with the good descriptor.
Or the solar's:
A solar takes normal damage from epic evil-aligned weapons, and from spells or effects with the evil descriptor.
It had always been my understanding that if a creature had an alignment subtype, that meant that their weapons were aligned. However, looking into the rules on alignment subtypes, this appears to be wrong. Alignment subtypes have a very specific allowance:
A creature with the good subtype overcomes damage reduction as if its natural weapons and any weapons it wields were good-aligned (see Damage Reduction, above).
In contrast, with the aligned weapon enhancements (holy, unholy), and in the align weapon spell, the wording is broader and includes damage reduction as something it bypasses as a result of being aligned:
A holy weapon is imbued with holy power. This power makes the weapon good-aligned and thus bypasses the corresponding damage reduction.
Align weapon makes a weapon good, evil, lawful, or chaotic, as you choose. A weapon that is aligned can bypass the damage reduction of certain creatures.
This feels like it could A) be an oversight (not unlikely, given this is early wording from 3.0 that carried into 3.5), or B), be an intentional choice to make bypassing of regeneration something you need specialized magic to do, rather than something monsters can do against other monsters.
Is my reading of the on alignment subtypes correct? Is there anywhere that it says that alignment subtypes also align the creature's natural weapons, as opposed to allowing them to overcome damage reduction as if they were aligned?
This question is about RAW. I'm curious if there's anything in the books stating explicitly that alignment subtypes should, or should not cause a creature to bypass regeneration. Relevant rules examples from the books or official articles elaborating on the game are valid answers to this question, and in the absence of anything else, citable information regarding developer intent would work.
Answers that consist solely of speculation or discussion of how you would personally rule this aren't going to be accepted (I would personally lean in favor of alignment subtypes, but this question is about analyzing the game, not my houserules).