Take heed, etc. - that is, See that thou be quiet (not seeking Assyrian aid in a fit of panic).
tails - mere ends of firebrands, almost consumed themselves (about soon to fall before the Assyrians, Isa 7:8), therefore harmless.
smoking - as about to go out; not blazing.
son of Remaliah - Pekah, a usurper (2Ki 15:25). The Easterners express contempt by designating one, not by his own name, but by his father’s, especially when the father is but little known (1Sa 20:27, 1Sa 20:31).