If you say that a comment is double-edged, you mean that it has two meanings, so that you are not sure whether the person who said it is being critical or is giving praise.
例句
Even his praise is double-edged.即使他的赞扬都说得模棱两可。
ADJ-GRADED
好坏相抵的;似好实坏的;有双重后果的
If you say that something is double-edged, you mean that its positive effects are balanced by its negative effects, or that its negative effects are greater.
例句
But tourism is double-edged, boosting the economy but damaging the environment...但旅游业具有两面性，既刺激经济增长但又会破坏环境。Riley's early celebrity proved to be double-edged.赖利的一早成名后来证明是把双刃剑。