1
general::
Phrase(s): brace up
to take heart; to be brave. • Brace up! Things could be worse. • I told John to brace up because things would probably get worse before they got better., Phrase(s): brace someone or something up
to prop up or add support to someone or something. • They braced the tree up for the expected windstorm. • They braced up the tree again after the storm.
McGrawhill's American Idioms And Phrasal Verbs
2
general::
Also, brace oneself. Summon up one's courage or resolve, as in Brace up, we don't have much farther to go, or Squaring his shoulders, he braced himself for the next wave. This idiom uses brace in the sense of "to bolster" or "to strengthen." The first term dates from the early 1700s, the variant from about 1500.
American Heritage Idioms