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' 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).