A.T. Robertson Commentary Revelation 16:2

"And the first went, and poured out his bowl into the earth; and it became a noisome and grievous sore upon the men that had the mark of the beast, and that worshipped his image." — Revelation 16:2 (ASV)

Went and poured out (απηλθεν κα εξεχεεν). Second aorist active indicative of απερχομα (redundant use like υπαγετε with εκχεετε, "go and pour out," in verse 1) and of εκχεω. Each angel "went off" to perform his task. For εξεχεεν see it repeated in verses 3,4,8,10,12,17.

Into the earth (εις την γην). This same use of εις after εξεχεεν in verses 3,4.

It became (εγενετο). "There came" (second aorist middle indicative of γινομα).

A noisome and grievous sore (ελκος κακον κα πονηρον). "Bad and malignant sore." Hελκος is old word for a suppurated wound (Latin ulcus), here, verse 11; Luke 16:21. See the sixth Egyptian plague (Exodus 9:10; Deuteronomy 28:27,35) and Job 2:7. The magicians were attacked in Egypt and the worshippers of Caesar here (13:17; 14:9,11; 19:20).