To prepare (oneself) for action
gird (or gird up) one's loins
A means or device that keeps something erect, stable, or secure
Two items of the same kind together
To give support
Look for anything to brace the door!
She looked around for something to brace the door and ended up leaning against it.
Katie rushed to the door, trying to brace it.
The door held, and she scrambled back to brace it.