In that day the LORD with his sore and great and strong sword shall punish leviathan the piercing serpent, even leviathan that crooked serpent; and he shall slay the dragon that is in the sea.
At the time when Israel shall be delivered, and the ungodly nations punished, God shall punish also the great enemy of the Church.
Sore - rather, hard, well-tempered (Hebrew, haqaashaah (H7186)).
Shall punish - answering to Isaiah 26:21, "the Lord cometh out of his place to punish ... the earth."
Leviathan - literally, in Arabic, from laawah (H3867), to twist; the twisted animal, applicable to every great tenant of the waters: sea-serpents, crocodiles, etc. In Ezekiel 29:3; Ezekiel 32:2; Daniel 7:1, etc.; Revelation 12:3, etc., potentates hostile to Israel are similarly described; antitypically and ultimately Satan is intended (Revelation 20:10).
Piercing - rigid (Lowth). Fleeing (Maurer and the Septuagint). Long, extended-namely, as the crocodile, which cannot readily bend back its body (Houbigant). Hebrew, baariach (H1281), from baarach (H1272), to flee across, or from side to side. The rapid darting of Satan from one side to another, when foiled on one hand, trying on the other hand to gain his point, seems to me intended, as other terms prove (cf. Job 26:13; 2 Corinthians 11:14, "Satan himself is transformed into an angel of light;" 2 Corinthians 2:11).
Crooked - winding or twisting, wriggling himself. His character answers well to his name above, "leviathan," the twister.
The dragon - Hebrew, taniyn (H8577), the crocodile. The Hebrew for "serpent" is nachash (H5175), the generic name.
That (is) in the sea - the Euphrates, or the expansion of it near Babylon.