bolster

to support or strengthen

To bolster is to put support underneath something that might sag: an argument, a mood, a shelf, a friend.

One concrete example bolstered her essay more than three vague claims.

A bolster is a long cushion. That is enough. Something is sagging, and support goes underneath it.

Evidence can bolster an argument. Rest can bolster your energy. A kind sentence can bolster someone who is trying not to fall apart. Keep the support-underneath image.