In all of the Seiken Densetsu games there have been animated Sword enemies which can fly around and attack on their own. Usually they can use Sabre magic on themselves.
Evil Swords are paired with Death Gauntlets and mindlessles fly around Dime Tower. These enemies would continue on into the other Seiken Densetsu games.
In SoM Swords are classified as Machines.
These swords are found in the Pandora Ruins. They sit in an ornamental holder until you get close enough and then they will whirl around in circles and stab at you.
Doom Sword / Element Sword (J)
Doom Swords are found in the Tree Palace, Underground City and the Mana Fortress. They use various sabre spells on themselves and they are most notable for guarding the Element Orbs in the Tree Palace alongside National Scars. They will occasionally drop Guardian Rings.
In SD3 Swords are classified as Demons.
The swords in SD3 start stuck in the ground, and when you get close they will jump out. Evil Swords live in Rolante Castle and have a Gale attack which speeds them up. They use a Whirlwind technique very very rarely.
Element Swords are found in the Mirage Palace and the Dark Castle. Like the Doom Swords in SoM they will always cast a random Sabre spell on themselves before a battle. They have a Hundered Stab technique.
In LoM Dainslaifs are classified as Poltergeists.
Dainslaif / Evil Sword (J)
These swords came to life in order to fight. They have the magical power of being able to turn into different weapons such as spears and flails and can also turn into a shield to defend themselves. As a pet they will protect you from staring attacks.