“in the end she.” The Hebrew is literally, “the end of her.” This is the genitive of agency, that is, it refers to the end that she brings about (cp. Bruce Waltke, New International Commentary on the Old Testament: Proverbs. Chapters 1-15, p. 302, n. 7).
This is one of the many verses that shows us that the truly wise person is the one who looks at the end result of a thought or action. Many things that seem “good” or “fun” in the beginning have a terrible, horrific, end.
“two-edged sword.” The Hebrew is literally, “a sword of mouths,” where “mouth” is plural, and the implied meaning is “a sword of two mouths” because swords often have two edges. The use of “the mouth of the sword” was a common idiom that is almost always translated “the edge of the sword” in English Bibles (the Young’s Literal Translation is an exception). There are more than 30 verses in the Old Testament in which swords are personified and people are said to be killed “by the mouth of the sword,” as if the sword was eating the enemy (cp. Gen. 34:26; Exod. 17:13; Num. 21:24; Deut. 13:15; 20:13; Josh. 6:21; 8:24; 10:28, 30, 32, 35, 37, 39; Judg. 1:8, 25; etc.).