Is “offrire la mano in amicizia” an idiomatic expression?

Question

I have read the following sentence in an Italian language learning tool:

Ti offrii la mia mano in amicizia. (= I offered you my hand in friendship)

I suspect that this may be an incorrect literal translation of the English expression "to offer one's hand in friendship to somebody" to Italian, partly because of the explicit possessive pronoun. Is this the usual way to express "to offer one's hand in friendship to somebody" or would be something else more usual (e.g., "tendere la mano a qualcuno in amicizia")?

Answer 1

First of all offrire qualcosa in segno di amicizia is perfect Italian. The first meaning in the Treccani dictionary is

offrire v. tr. [lat. *offerīre per il class. offerre, comp. di ob- e ferre «portare»] (io òffro, ecc.; pass. rem. offrìi o offèrsi, offristi, ecc.; part. pass. offèrto). – 1. Presentare o proporre a qualcuno una cosa (materiale o no, ma che comunque si ritiene utile o gradita) perché la prenda o l’accetti; manifestare con parole o con atti tale intenzione.

Offering one's hand implies “in order to shake it”.

You're right about the possessive: in this case “la mia mano” is bad Italian; nobody would offer someone else's hand, so

Ti offrii la mano in segno di amicizia

The possessive may be used: il martello cadde sulla mia mano is grammatical, but it would need some kind of specification (maybe implied by the discourse), because it emphasizes that the hammer fell on my hand and not somewhere else. In absolute sense it would be il martello mi cadde sulla mano.