Jamieson, Fausset and Brown on Revelation 16:5

5. angel of the waters--that is, presiding over the waters.

O Lord--omitted by A, B, C, Vulgate, Syriac, Coptic, and Andreas.

and shalt be--A, B, C, Vulgate, and Andreas for this clause read, "(which art and wast) holy." The Lord is now no longer He that shall come, for He is come in vengeance and therefore the third of the three clauses found in Re 1:4, 8; 4:8 is here and in Re 11:17 omitted.

judged thus--literally, "these things." "Thou didst inflict this judgment."