One of those files should go (or do they have different purposes ?). Currently arch.list is used in portage.py to determine invalid ACCEPT_KEYWORDS settings, but repoman uses keywords.desc to check for KEYWORDS.
keywords.desc is not a definitive set. arch.list is keywords only, and is how repoman should glean that info.
That last statement was wrong. I don't care which we keep as long as it's the only one in use.
a little poll on -dev showed 2:0 in favor for keeping arch.list.
Created attachment 25696 [details, diff] Patch to s/keywords.desc/arch.list/
Been released for a while...