How does ウァ differ from ワ and ヴァ?


I know Wine is written as ワイン. I've also seen Whiskey as ウィスキー. In both
english words, the 'w' sound are relatively similar (although slightly
different). I'm assuming ウァ would be somewhat like ワ. But then there is
'[Valentinus](http://ja.wikipedia.org/wiki/%E3%82%A6%E3%82%A1%E3%83%AC%E3%83%B3%E3%83%86%E3%82%A3%E3%83%8C%E3%82%B9)'
written as ウァレンティヌス and I don't understand why ウァ is used as VA (instead of
ヴァ).

Could anyone please point out what the differences (especially between ウァ and
ワ) are, I think I'm confused (maybe because we don't have the english 'w'
sound in German).




It seems that there is a tradition to describe the sound of Latin /va/ as
ウァ(which would be pronounced the same as ワ) in Japanese.

This might spill over into Latin words used in actual Japanese, but the result
is mostly a stylistic effect and/or a snobbery effect. There is only one /w/
phoneme in Japanese.




Latin scholars in Japan seem to like using ウァ instead of ワ.
[Wikipedia](http://ja.wikipedia.org/wiki/%E3%82%8F) says
"一部の外来語で、発音が同じ/wa/であってもワの代わりにウァと書く場合がある。一般には使われないが、ラテン語のvaを古典式発音で音写する際に用いられる（例：ウァレンティヌス、ミネルウァ）。"

