Faint-hearted and Weak in the knees

Faint-hearted adjective - Lacking conviction or boldness or courage.

Weak in the knees and faint-hearted are semantically related. In some cases you can use "Weak in the knees" instead an adjective phrase "Faint-hearted".

Faint-hearted and weak in the knees are semantically related. Sometimes you can use "Faint-hearted" instead an adjective phrase "Weak in the knees".