Generally in the Seiken Densetsu series there are very few humanoid enemies. Knights are one of the few acceptions. The Knights commonly fall into three different groups: Machines, Demons and Poltergeists. Only SwoM and FFA contain Knights which are actually proven to be human besides the Mech Rider in SoM. Their weapons are some of the most diverse in the series ranging from swords to ball and chains and even spears. These are usually some of the strongest enemies. In SwoM new Granz Knights appeared along with Granz Mages. The Granz Knights used both Javelins, Swords and Bows.
The closest thing in FFA to the other Knights in the Seiken Densetsu series is the Dark Stalker found in Glaive Castle. The name Dark Stalker would later be used for a Ninja in SoM and a Knight in LoM. It is always paired with Wizards. It attacks by walking around and stabbing with its sword.
Dark Lord is finally confronted in his castle. He fights simply by charging you with his sword. After you defeat him Julius comes and lets you know that he was just using Dark Lord to further his own ambitions. Then he blasts you away, and the story takes a new turn.
In SoM Knights are classified as Machines.
Armored Man / Armor Knight (J)
These enemies carry large balls and chains and can swing them with such force that they lif off of the ground like a helicopter. Armored Men are very slow enemies, but while in helicopter mode they can move at surprising speeds. Armored Men are found in Northtown working for the Emperor, and there is even one in the Mana Fortress.
These much darker versions of Armored Men frequent the Dark Palace. They can cast Wall on themselves to keep magic from hitting them. Sometimes they will cast Dispell. One of these also made its way into the Mana Fortress. If you are very lucky they seem to have a higher chance of dropping Shadow Zeroes than most enemies.
These Knights are the most powerful normal enemies in SoM. They can cast Lucid Barrier to keep themselves from taking damage from weapons. Even without its wall on it very rarely takes physical damage. They are only found in the Mana Fortress. They drop both Faerie Cloaks and a Whip Orb.
Mech Rider / Machine Rider (J)
The Mech Rider is not as much a Knight as it is the character Sheex dressed in armor riding on a mechanical type of hovering motorcycle. It attacks by ramming into you as well as shooting off missiles. It is very fast and uses multiple boost spells on itself. This is the one case in SoM where a Knight is actually a human character. There are three Mechriders in the game: one in the desert, on top of the Northtown Castle, in the Mana Fortress while it is still a part of the Tree Palace.
In SD3 Knights are classified as Demons.
These enemies are very similar to Duran’s Gladiator class. They attack with a giant sword and have a devastating Whirlwind technique which damages everyone on screen. One of these enemies appears as the first opponent for Duran in his quest.
These purplish versions of Armor Knights are similar to Duran’s Swordmaster class. They use the full screen Vaccuum Sword technique as well as many random sabre spells. They are known to use their abilities when they take lots of damage quickly.
These bluish grey versions of Armor Knights are similar to Duran’s Lord class. They use a one target Circle Cut technique but make up for the lack of targets by being able to heal themselves.
These tanks of enemies are similar to Duran’s class Duelist and share a name with one of the main antagonists of FFA. They posess the mighty full screen Eruption Sword and usually cast dark sabre on themselves. They retaliate with their special technique often when taking damage.
This enemy looks very similar to the Dark Knights in SoM. This enemy posesses all of Duran’s abilities.
In LoM Dark Stalkers are classified as Demonic.
Though sharing a name with an SoM Ninja, these enemies are much more similar to the knights from SD3. They have the ability to shoot their sword through the ground at you. They also have sword attacks which can catch your character in a flurry of hits. They can be found in the Underworld, Bone Fortress and Tower of Lieres usually. As a pet their synchro adds a darkness effect to your weapon.