Marth (SSBB)/Forward aerial
Marth does a forward vertical slash from top to bottom with his sword, doing 10% damage on the base of the sword and 13% with the tip. Although it doesn't have much knockback if hit on its base, it has KOing potential at around 150% when hit on the tip, and can KO earlier when used near the edges of the stage. Hits with an arc which covers his entire front body within frames 4 to 7. An extremely useful move for spacing, edgeguarding, and aerial approaches, due to its very quick speed and a long-ranged disjointed hitbox that gives it a long, safe range, and when used properly with reads on a recovering opponent, can create a wall that is difficult to get through without being damaged. At low percents, due to its low ending lag and good damage, it is an excellent combo move and is commonly used multiple times in a row to rack up damage, or combined with other aerial attacks. With its disjoints, even against longer ranged moves (which greatly extend their hitbox, like King Dedede's Back aerial) it is possible to space away and still hit them with Fair without Marth himself getting hit by taking advantage of the opponent's extending of their hurtbox.
With its range, speed and having low amount of ending lag it can be a great tool to offensively pressure Marth's opponent when spaced correctly. The move only has 9 frames landing lag, making it safe to land with. The move has a frame advantage on shield of -4 when not tippered and -8 when tippered, both in the case of hitting a shield exactly one frame before landing. If Marth lands the sourspot, he can shield any Out of Shield punish (except for Mario's Super Jump Punch) and if the opponent tries to grab him, he can either Dolphin Slash or spot dodge through the grab, making it perfectly safe. The tipper is theoretically punishable however in almost all cases, the opponent is pushed too far away to punish Marth (especially when spaced properly), making the tipper even safer on shield.
Considered Marth's best aerial and arguably the best forward aerial in the game. Its only noticeable flaw is its low hitbox duration, making it require precise timing to consistently space with it.