Snatching them out of the fire (ek puros harpazontes). Present active participle of harpazō, old verb, to seize. Quotation from Amo 4:11 and Zec 3:3. Cf. Psa 106:18. Firemen today literally do this rescue work. Do Christians?
And on some have mercy with fear (hous de eleāte en phobōi). In fear “of the contagion of sin while we are rescuing them” (Vincent). For this idea see 1Pe 1:17; 1Pe 3:15; 2Co 7:1; Phi 2:12.
Spotted (espilōmenon). Perfect passive participle of spiloō, late and common verb (from spilos, spot, 2Pe 2:13), in N.T. only here and Jam 3:6.