Usage of "Non avere né arte né parte"

Question

I know that this phrase describes someone who has not got any skills and is poor but I would like to understand when it is used for example: just to say one is penniless, poor or in a more particular way. I am asking this because I want to find the exact English equivalent.

Answer 1

Let me quote from Carlo Lapucci, Dizionario dei modi di dire della lingua italiana, Garzanti-Vallardi, 1979, p. 13:

Non avere né arte né parte
Non conoscere un mestiere, non avere nessuna abilità e non avere né beni né appoggi.
Il detto fa probabilmente riferimento alle arti (maggiori e minori), e alle corporazioni medievali delle quali uno faceva parte secondo l'attività che svolgeva. Le corporazioni entravano poi nelle divisioni politiche (parti). C'è anche il detto: “Chi ha arte ha parte”.

That is, «Not knowing a trade, having no skills and having neither goods nor supporters. The saying probably refers to the Arti (major and minor ones) [1], and to the medieval guilds of which one was part according to the activity he carried out. The guilds, in turn, were involved in the political divisions (parti [2]). There is also the saying: Chi ha arte ha parte.»

To add a personal comment as an Italian mother tongue, more than a simply penniless person, I'd say it of someone who is a good-for-nothing, who hasn't a say in anything, nor seems to be able, or willing to.

[1] See for instance the Arti di Firenze.

[2] Compare this with “(political) parties”.