What would 'be that as it may' be considered in English grammar?

I suppose many will say it's an idiom. The reason I'm asking though is that I'm trying to find a collection of phrases like 'be that as it may', 'much to his chagrin', 'far be it from me' etc... I suppose they're more academic in nature, possibly even transitional. How would you define sayings like these? Searches for idioms just come up with sayings like 'a bird in the bush is worth two in the hand' and 'let the chips fall where they may' I guess what I'm really looking for are academic transitional phrases that make my papers flow better. I want them to be articulate, but not to the point of being pretentious. I don't know, maybe what I'm looking for doesn't exist. Any suggestions?