Re: A Luthier is Someone Who . . .
I work closely with a Master Luthier. Although he chooses to use the title
"Maker of Fine stringed instruments". He is without question a Luthier. He builds guitars from blocks of wood. He builds guitars from parts He does restoration of Vintage guitars, and he does setups.
I have seen him replace a missing piece of wood from the top of a 1942 D'Angelico and you just can't tell where the repair was done.

I have seen him replace some badly damage routing on an early 50's Stratocaster and mnake look like it was never touched.
I have played a Parlor sized Acoustic guitar that he made from blocks of wood, and it is by far the best sounding small guitar I have ever played. I have played an Electric Archtop that he made also from blocks of wood. It sounds as good as any Vintage Gibson I have played. I have also played a Acoustic Archtop that he just completed and found it to be Awesome considering the strings had only been on about a day.
All of these things make an individual a Master Luthier!! The ability to repair a damaged guitar is much more difficult than building something from the ground up. The trick is to make the repai look like it never happened.
If you want to see some of his work look here.
www.mirabellaguitars.com