Being darkened (εσκοτωμενο οντες). Periphrastic perfect passive participle of σκοτοω, old verb from σκοτος (darkness), in N.T. only here and Revelation 9:2; Revelation 16:10.

In their understanding (τη διανοια). Locative case. Probably διανοια (δια, νους) includes the emotions as well as the intellect (νους). It is possible to take οντες with απηλλοτριωμενο (see Ephesians 2:12) which would then be periphrastic (instead of εσκοτωμενο) perfect passive participle.

From the life of God (της ζωης του θεου). Ablative case ζωης after απηλλοτριωμενο (Ephesians 2:12).

Because of the ignorance (δια την αγνοιαν). Old word from αγνοεω, not to know. Rare in N.T. See Acts 3:17.

Hardening (πωρωσιν). Late medical term (Hippocrates) for callous hardening. Only other N.T. examples are Mark 3:5; Romans 11:25.