Play down my sword and shield

They call it l'esprit d'escalier, don't they, the perfect parting shot constructed just after the imperfect parting. But what do you call it when you unexpectedly get a chance to say something that you intended to say years ago, something that you've felt needling the back of your tongue and needing to be said ever since then, only to find when you actually come to say it that it leaves nothing but a stale, flat taste in the mouth? What do you call it when you're awarded a free goal kick two years after rain stopped play, and you take it because your feet have reflexes deeper than your thoughts, only to find that the goalposts have long since moved, and that all you've succeeded in doing is kicking a slightly-deflated ball into the garden of an old man who's too far gone now to notice anyway?

No, don't tell me the word for it. You can't have your ball back. You can go and look round the garden, though, and if you're wise, you won't waste time looking for something that's long since lost, when the garden's full of flowers and fruit. Tell your friends what you find there. And be more careful next time.