here's how I imagine it being used:Part of the problem is in breaking up idiomatic phrases. I think you want that first sentence to mean something like "acting with (reckless) abandon". Leaving out the "with", I will think his parents left him on a doorstep as a baby, i.e. he was abandoned, he is an abandoned child.
it was just the first example i could come up with because I have a friend in a band called the Reckless Abandons. That got me wondering about what, if anything, you call a noun being used, I guess, as an adjective.I don't understand what you are asking, I'm afraid. Have you invented "He is an abandon"?