LW stands for Light Weight. Meaning it has relative relation to someone of something.

Style with Ease

A term used by (mostly) people with eating disorders meaning lowest weight

Lord-willing. In other words, if the Lord is willing or if it is the Lord's will. See James 4:13-15.
This abbreviation precedes some likely but not absolutely certain prediction.

"love weed", to be used interchangeably with any term for marijuana, but used in order to not attract attention to what you are discussing.. or to be used as a farewell at the end of a conversation between two weed addicts

Lucky Win
In any competitive game where one wins despite percentages or inferior level of skill using luck
(mainly used in Poker)

meaning "Last Word" in an argument or after an online game has concluded.