「軽くならいいけど」「うむ、では金的と目潰しは有効にするか？」

「」「、？」

'Light touch is fine, but...' 'Hmm, then shall we allow groin shots and eye-pokes?'

Literal

''Light-contact [if-なら] good-[but-けど]'' ''Yes, then crotch-attack [and-と] eye-poke [topic-は] effective [to-に] [volitional-するか]?''

A sparring/fighting match negotiation. 金的 (きんてき) literally 'golden target', a euphemistic but direct term for a groin attack in martial arts — the 'golden target' refers to the testicles. 目潰し ('eye-crush') is 'eye-poke, eye-gouge'. 有効 ('valid, effective') here means 'counted as a legal hit' in match rules. 軽くなら ('if light/gently') frames the whole exchange as negotiating the level of severity allowed.