And as I said before, your tendencies to pronounce every other part of the word in english, probably causes you to not pronounce it as a Japanese person would. So just because your adding that "eh" or "ay" or whatever it is at the end of same, or mune, doesn't mean your pronouncing the entire word correctly.
I do study Japanese and I will have to assure you that I am pronouncing it correctly. I am only giving the pronunciation key in such a way that people that don't know any Japanese would be able to pronounce it more or less correctly. If I found some way to record it, I'd be more than happy to say it out loud...

Mind you, I am not telling you have to pronounce it a certain way. I don't really care how you pronounce it, but that doesn't change the fact that there are still proper ways to spell and pronounce these words.

Look if we're going to pronounce everything as it would be in Japanese we're going to have to start calling Cloud "Crowd", and Final Fantasy "Finar Fantaji".
Of course we wouldn't want to pronounce western names the way the Japanese would, since they're supposed to be English names anyway. But Murasame and Masamune are native Japanese words; and should be treated like any other loanword (in theory...).
Actually, I'm in a Japanese class and my teacher MS. NEZUKA told us distinctly that the letter "r" in Japanese "ra" "ri" "ru" "re" "ro", is pronounced as an "l" so it would be "la" "li" "lu" "le" "lo".

Therefore, Cloud is Cloud, Final Fantasy is Final Fantasy and Barret Wallace is Ballet Wallace.

Spelling would be something like Kuraodo Sutoraifu, Fuainaa Fuaantashii, and Beereto Waresu.
The pronunciation of 'l' and 'r' in Japanese really depends on the dialect of the person speaking. It is more accurate to say that the 'l' and 'r' sounds are the same sound in Japanese; as is the case with 'b' and 'v, 'h' and 'f', and other 'substitute sounds'.

The transliterating of foreign words into katakana does not mean that a person's name is going to be spelled in romaji when it is in English...Square almost always uses official romanizations of characters' names, and Barret is no exception.