Laudator Temporis Acti

Vergil, Aeneid 12.788-790 (tr. H. Ruston Fairclough):

At full height, in arms and heart renewed--one trusting to his sword, one fiercely towering with his spear--breathless both, they stand facing the War-god's strife.

olli sublimes, armis animisque refecti,
hic gladio fidens, hic acer et arduus hasta,
adsistunt contra certamina Martis anheli.

Is anheli nominative plural (modifying Turnus and Aeneas) or genitive singular (modifying Mars)? T.E. Page in his commentary favors the former, and states:

Many, however, render 'of breathless Mars' (le combat qui essouffle, Benoist), making anheli gen. sing. on the ground that the combatants were now animis refecti. But surely, however 'refreshed in spirit,' both warriors must have been a little out of breath still, and the description of them as facing each other 'panting' is highly natural, whereas Mars anhelus is a most startling phrase.

On the other hand, Lucio Cristante, La calamita innamorata (Claud. carm. min. 29 Magnes; con un saggio di commento), Incontri triestini di filologia classica 1 (2001-2002) 35-85, cites (at 70) Servius ad loc. (alii 'certamine' legunt, ut sit sensus: adsistunt contra se in Martis anheli certamine), where the word order favors anheli as an attribute of Martis; Dracontius, Romulea 10.576 (no quotation, and the text is unavailable to me); Reposianus, De Concubitu Martis et Veneris 14 (Gravidus anhelat); id. at 117 (ardor (sc. Martis) anhelat); and Carm. Min. App. 5.76 (luctamen anhelum).

Page and Cristante don't cite any Greek parallels. On breathlessness in war, see Homer, Iliad 11.801 = 16.43 = 18.201 (tr. A.T. Murray):

For scant is the breathing-space of battle.

ὀλίγη δέ τ᾽ ἀνάπνευσις πολέμοιο.

Hesiod, Theogony 797 uses ἀνάπνευστος for ἄπνευστος to mean breathless.

See also Homer, Iliad 16.109-111 (tr. Murray):

And evermore was he distressed by laboured breathing, and down from his limbs on every side abundant sweat kept streaming, nor had he any wise respite to get his breath withal, but every way evil was heaped upon evil.

αἰεὶ δ᾽ ἀργαλέῳ ἔχετ᾽ ἄσθματι, κὰδ δέ οἱ ἱδρὼς
πάντοθεν ἐκ μελέων πολὺς ἔρρεεν, οὐδέ πῃ εἶχεν
ἀμπνεῦσαι· πάντῃ δὲ κακὸν κακῷ ἐστήρικτο.

In Homer's Greek (Iliad 16.109) we see the word ἄσθμα, which is the same as our English asthma.