When FFXII was still young in development and we got the first information on the characters, Balthier's name was first romanized into Barufurea, or Balflear. As the japanese language doesn't use th-sounds, it was hard to imagine what the official english translation of it would be.
Balthier kind of has a familiar clang to it, don't you think? When I tried to look it up, I could hardly find anything but links connecting to FFXII. Other names that sound similar are Bhaltair, which is a Scottish form of Walter, and Balder, which was the name of Odin and Friggs son in norse mythology and means "prince".

Balthier is one of the three permanent party-members with the priviledge of a last name, together with Ashe and Basch.(Heh, writing their names together makes me snicker XD)
The lastname Bunansa indicates that Balthier could somehow be related to Mustadio Bunanza from Final Fantasy Tactics. As you probably already know FFXII is set in the world of FFT, Ivalice. Mustadio is an engineer workclass that wields a gun, similar to Balthier. I have yet to play FFT, but as soon as I do this section will be updated~ until then you can get more information on Mustadio and his familyline at the fansite Aim! Aim!