“a greeting of blessing.” The Hebrew is just “bless,” but a blessing was used as a greeting.
“our lord.” This is a grammatical plural, literally “lords,” but it refers to a single “lord,” Nabal (see commentary on 1 Kings 1:43).
“he shrieked at them.” The noun form of “shrieked” is the name of a hawk. Thus the men bring in the idea that Nabal screamed at the men like a hawk would shriek at something. Its never good to shriek at the anointed king of Israel, only trouble can follow.