Please help with the bold line. たちどころに擦り傷が治る練り薬や、野宿に役立つ安眠ポプリやら疲れがよくとれる湿布やら、痒いところに手が届く日常的なグッズが満載だ。 なんか美容液までもらってしまって、正直いらねーと返そうとしたんだけど、なんとコレ、塗ると魔力回復が促進され、軽い攻撃は跳ね返すという無駄に高性能なシロモノだった。 Many thanks.
A quick tl: Somehow I received this cosmetic cream (unwillingly), and I even tried to return it, but anyways, it is an overly/excessively useful thing which promotes magic regeneration, allowing one to recover from a small attack.
→ I was even given some kind of beautifying serum. I candidly said I didn’t need it and tried to give it back, but the man claimed that the frivolously potent gunk would "boost mana recovery and repel mild attacks when applied". @yamitokaze didn't do too bad, but there's a couple of clauses in there that are quotes of the characters' speech. I think the second one works better as a literal quote attributed to the speaker. (A Japanese reader would already know who the speaker is from context, but English has to spell it out.)