It was the ancient Romans who first used their “palmarius” to describe someone or something extraordinary. “Palmarius” literally translates as "deserving the palm." But what does that mean exactly? Was it inspired by palms of hands coming together in applause? That would be a good guess, but the direct inspiration for “palmarius” was the palm leaf given to a victor in a sports competition. That other palm, the one on the hand, is loosely related. The Romans thought the palm tree's leaves resembled an outstretched palm of the hand; they thus used their word “palma” for both meanings, just as we do with "palm" in English.
This reminds me of a bit of history that I long to see repeated:
On the next day the large crowd who had come to the feast, when they heard that Jesus was coming to Jerusalem, took the branches of the palm trees and went out to meet Him, and began to shout, "Hosanna! BLESSED IS HE WHO COMES IN THE NAME OF THE LORD, even the King of Israel."- John 12:12-13
I am also reminded of the words of the Psalmist:
I call upon the LORD, who is worthy to be praised... Psalm 18:3