Meta Knight (SSBB)/Down smash
Meta Knight slashes in front of him and then quickly slashes behind him, with the back slash being stronger than the front. This is considered Meta Knight's best KO move, having a combination of extremely fast startup lag, great transcendent reach, and the back slash being his second strongest move from neutral. It is also considered the best down smash in Brawl on par with Wolf's, as not only has solid KO power, but it is also among the fastest down smashes. It comes out on frame 5, giving it the 4th shortest startup lag out of any down smash along with Mario's, Luigi's and Pit's. It also has an FAF of 35, making it tied with Wolf's and R.O.B.'s for having the second shortest total duration out of any down smash (although it does have relatively higher ending lag than both). Additionally when the move is buffered out of another animation, the move is one frame faster, making it tied for having the lowest startup lag and total duration out of every down smash. It also has among the best reach, making it difficult to punish if used and spaced correctly, especially due to its relatively low ending lag.
Both slashes have high base knockback, and can KO especially well near blast lines. Their knockback scaling isn't as high, though the back slash has enough to still KO heavier characters reliably even with DI and momentum cancelling factored. The front slash however can have difficulty KOing under 150% under the aforementioned conditions (though due to its start-up, it can often catch opponents offguard and keep them from DI'ing properly). Due to the back slash still coming out reasonably fast, Meta Knight players will often turn around before using down smash to land the stronger back slash (the back slash is also less punishable, due to greater shield stun and the move being nearer to the end of its duration). While usually conserved by competent Meta Knights to keep the move fresh, its effective capability as a "get off me" move sees it used as a stronger alternative to Shuttle Loop and Mach Tornado when the Meta Knight is being pressured.
Overall, Meta Knight's down smash is an excellent and not difficult to use move that is heavily used in all levels of play, and that is commonly seen as straddling the broken threshold.