Finally (to telos). Adverbial accusative. Conclusion, not of the Epistle, but only of the addresses to various classes. No verb (este imperative, be) here.
Likeminded (homophrones). Old compound (homos, phrēn), here only in N.T.
Compassionate (sumpatheis). Old adjective (sun, paschō), in N.T. only here and Rom 12:15. Our “sympathetic” in original sense.
Loving as brethren (philadelphoi). Old compound (philos, adelphos), here only in N.T.
Tender-hearted (eusplagchnoi). Late and rare compound (eu and splagchnon), in Hippocrates, Apocrypha, in N.T. only here and Eph 4:32.
Humble minded (tapeinophrones). Late compound (tapeinos, phrēn), in Plutarch, Pro 29:23, here only in N.T.