Armor Knight is a Spirit effect in Super Smash Bros. Ultimate that provides large buffs to its user’s attack and defense stats. Its defensive enhancements were unrivaled across the board, with the bonus’s only drawback being a slight reduction in movement speed. Armor Knight became popular after the banning of Super Armor, but was itself banned several months later.
Armor Knight was an extremely centralizing bonus in the Ultimate amiibo metagame, and was considered the undisputed best setup for almost every fighter. Given that it only occupied two Spirit slots, it was often paired with Move Speed ↑ to negate Armor Knight’s sole drawback.
Though Armor Knight seemed fair on paper, in-game calculations proved the effect to be inherently unbalanced. During its run, many amiibo ran Armor Knight and Move Speed ↑ alongside maximum defense, resulting in fighters that were nearly impossible to defeat. Several characters were considered broken with this loadout; Lucas, Piranha Plant, and King K. Rool (and other fighters with great recoveries) were nearly undefeatable thanks to their high defense.
Armor Knight was eventually banned alongside Autoheal and Great Autoheal; by the time Armor Knight was banned, however, the damage had been done: many trainers had lost interest in the Spirits metagame due to its heavy focus on defense.