Be it = if it is. Yes, it's a little old fashioned and definitely formal.

Hi Sébastien, "Be it" means "whether it is" or "whether it be" We use it to describe something you will do for sure but how, when and where may not be certain. Your example sentence is a perfect example of how to use it. Here is another similar use: "I will watch that movie, be it this week, next week or the week after" so you know you'll watch it but you're not sure when. I would say it's formal, yes, though not strictly speaking. Hope this helps but please let me know if you have any questions. Sinead

The present subjunctive ('be' in this case, which is like 'il soit' in French) is almost extinct in modern English, but it is used in a few common expressions such as 'be it A or B'. These expressions aren't exactly old-fashioned -- 'if need be' and 'come hell or high water' are used quite often -- it's more a matter of using them in the right context.