cut both ways

cut both ways (to have both advantages and disadvantages) — быть обоюдоострым;
something cuts both ways (used when speaking about something that can serve both sides or an argument.) — это обоюдоострый вопрос; это палка о двух концах;

Example: The Internet cuts both ways – it not only opens borders, it draws boundaries between the people who have it and those who do not. (CIDI)
Example 2: TJust remember that what you're saying cuts both ways.
Example 3: I'm afraid his evidence cuts both ways and won't be of much use to us.

see also
[палка о двух концах]
[every cloud has a silver lining]