The following is said immediately after the protagonist wins without having to fight, as he previously stated he would:
I said I'll win without fighting.
I would have expected the English translation to be expressed in Japanese as 「闘わずに勝つってな」or 「闘わないで勝つってな」. In fact, I find the use of する there somewhat confusing. Is する referring to the actions leading up to 勝つ or is it referring to 勝つ itself, or is it simply grammatical and lacks a concrete meaning?
Could someone please explain how 闘わずして勝つってな and 闘わずに勝つってな differ in overall meaning?
Also, if it is simple and for my information, when would you use 戦う rather than 闘う?