concubuere seems sufficiently warranted by concubitus in 4. 8. 36 and by Varro, L.L. 7. 78 concubium a concubitu dormiendi causa dictum (cf. ibid. 6. 7 concubium appellarunt, quod omnes fere tune cubarent: also Cic. Rep. 4. 4, Cypr. Epist. 4. 3, 4). Propertius' tendency to use words in their etymological sense where this is abnormal is exaggerated by Postgate (Sel. Eleg. p. xc), but insinuentur (3. 9. 28) and impuros (4. 8. 22) are valid examples, perhaps also ingrata (1. 10. 23). One reason why concubuere stands here instead of procubuere (which BB. consider an almost necessary correction: cf. Ov. Met. 3. 23) may have been a reluctance to begin two consecutive words with the same prefix.

saepe (‘often’) is rather pointless, but not intolerably so for Propertius. Conjectures which make it abl. of saepes are not attractive. It might be better to substitute nempe (for the confusion see Housman, luuenalis, pp. li f.). But Lactantius, Inst. 2. 6. 14, quotes the text in its present form.

proelia nuda, ‘weaponless battles’, is good Latin, in defence of which Passerat and subsequent editors cite Stat. Theb. 1. 413 nudamque lacessere pugnam. Housman adds Sil. 6. 46 abstulerat firs arma; tamen certamine nudo / inuenit Marti telum dolor.