In English is one and the same word with one single meaning. And +Paul used exclusively haigios which is equivalent only most holy (chaciyd).
Again, this is an example of man-made bible, subject to faulty interpretation because of linguistic and other preferences of the author(s).
Faulty interpretation leads to faulty comprehension and faulty comprehension to faulty belief. That's why individuals cannot just read the bible and believe correctly.
Well do you want to use the Hebrew words of "faithful" and "holy" for earthly believers? Dictionary.com defines "saint" as a person of great holiness, virtue, or benevolence. The Psalms call believers "holy". Sounds like the same thing to me. The "faulty" interpretation is a stretch IMHO.
How would YOU define these Hebrew terms and does it make any difference?