The vision of his wife that our speaker has in "Methought I Saw my Late Espoused Saint" is all about love and purity. Seriously, she's practically glowing with the stuff. The seamlessness between the wife's outer appearance and her spiritual qualities signifies that the boundary between body and soul has collapsed now that she is in heaven, which means the (perfect) state of her soul is evident in her outward appearance.
All that business comparing his wife to a female figure from the Hebrew Bible is to drive home the fact that now that she's in heaven, the speaker's wife is free from sin and totally pure.
The speaker's ability to make out his wife's virtues in her "person" indicates the collapse between the soul and the body that occurs after death.