A person's looks are a double-edged sword. Sometimes it works in your favour, sometimes it works against you.

一个人的相貌是一把双刃剑。有时它对你有利，有时又对你不利。

Advanced technology is usually a double-edged sword, which can bring people both benefits and harms.

先进的技术通常是一把双刃剑，它可以给人们带来好处和危害。

As far as I'm concerned, the Internet is a double-edged sword. We must remain skeptical of Internet information.

我认为互联网是把双刃剑。我们必须对网上的信息保留怀疑态度。

Since technology is a double-edged sword, the development it brings and its potential threats are two sides of the same coin.

技术是一把双刃剑，因此它所带来的发展及其潜在威胁是紧密相关的。

Let us look at an idiom: kill two birds with double-edged sword.

我们再看一个成语：一举两得/一箭双雕。