Ludociel is one of the strongest characters in the Seven Deadly Sins universe, and easily its most morally contentious. The leader of the Four Archangels and a devoted servant to the Supreme Deity, he enacts his master's will to demolish demons whatever the cost.
Though he works alongside the forces of Liones in order to defeat the Ten Commandments permanently, he has conducted himself in a way that is not explicitly noble. By analyzing his history, we can determine if his decisions ultimately made him a hero, or just as evil as the threats he hoped to expunge.
10 Hero: Sariel & Tarmiel Helped Keep Him In Check
Sariel and Tarmiel were the other two archangels who assisted Ludociel in his ventures. They often served as a moral check for when his actions went too far, entailing that through their guidance, their leader might not employ excessively depraved methods.
Further, they are useful to the war effort. With their combined strength, they apprehended Estarossa and would have successfully defeated him if he had not consumed the other members of the Ten Commandments, augmenting his strength and returning him to the battle.
9 Villain: Using Fraudulent Light To Brainwash People
When Ludociel made his presence known to the humans, many were less than thrilled to greet him. Some had reservations about his intentions, especially since the servants of the Supreme Deity were often associated with the Demon King himself.
In order to assuage the dissenters, Ludociel cast a spell called "Fraudulent Light" on them, imbuing them with false confidence and implacable faith in his ability. Effectively, he had brainwashed them into serving him and fighting until their bodies gave out. This was a chilling demonstration to what little value he placed in human life.
8 Hero: Joining Liones
Just as Ludociel had fought demons long ago, he had pledged his allegiance to the humans in order to liberate them from the many monsters marauding across the countryside. He did so without stipulation, uninterested in dominating them himself after his task had been complete.
The only condition behind his service was that he sought to kill Meliodas as well. However, considering that he had agreed to become Demon King by this time (albeit for an excusable reason), it's difficult to condemn the Archangel for wanting to see him brought down and the safety of the realm secured.
7 Villain: Using Demons As Shields
In order to draw the Ten Commandments out, Ludociel used many demons as fodder during the previous Holy War. Though it may have been morally questionable if they were enemy combatants, it was a horrifying war crime since many of those he had purposed toward this end were innocent and unaffiliated with the current conflict.
It was one of the most grotesque misuses of his power and incited the wrath of Derieri and Monspeet. In this regard, his plan was successful, though only because the Archangel was willing to deign to means lower than the demons themselves.
6 Hero: Attacking Zeldris
During Merlin's negotiation with Zeldris, Ludociel attacked the demon with a gigantic spear of light. This allowed her to escape from their confrontation unharmed and significantly damaged their opponent.
Moreover, it enabled those under watch by the Demon King's army to escape without forcing a price to be paid for their lives. Since Ludociel was unaware of the negotiation which was occurring, it is difficult to accuse him of being dishonorable for intervening in the sorceress's affairs and striking out against his sworn enemy.
5 Villain: Jumping Escanor
When Ludociel had witnessed Escanor's "Sunshine" ability, he immediately jumped him and attempted to take his life. Fortunately, the Pride Sin was able to dodge his attacks with little difficulty, resulting in a banter between the two of them after a brief skirmish.
However, the Archangel's zealousness could have torn a rift in the tenuous alliance between the newly christened allies. Should he have been less forgiving (or should Ludociel's efforts have wounded him noticeably), it could have portended a disaster that would leave both forces in ruin and enable the demons' success in the war campaign.
4 Hero: Attempting To Finish Off Monspeet & Derieri
When Monspeet and Derieri had been defeated, Ludociel attempted to land the finishing blow. While this was generally viewed as a villainous action by the other characters (including Elizabeth and even Meliodas himself), it is difficult to condemn it considering what their intervention had resulted in.
While it is true that both demons would have a change of heart later in the story, it was not before they had murdered dozens of innocent people and wantonly consumed their souls. Should Ludociel have vanquished them, he would have saved many innocent lives in the process.
3 Villain: Serving The Supreme Deity
The Supreme Deity was to the Goddess race what the Demon King was to the demons. Similarly, she was just as obsessed with dominating her counterpart, willing to deign to any lengths in order to defeat him.
When Meliodas and Elizabeth attempted to put an end to their conflict, it resulted a severe punishment for both of them, one designed to exploit their love and turn it into and unconventional torment. Ludociel's service to her evinces that he excuses her sadism.
2 Hero: Saving Gilthunder
Obsessed with Gilthunder, Vivian had abducted him and insisted that he would eventually love her. This was much to the distress of Margaret, who implored Ludociel for help in order to save her betrothed.
The Archangel would agree, tracking down the rogue sorceress and slicing her throat with a brilliant beam of light, guaranteeing Gilthunder's freedom and allowing him to return to the ranks of Liones. It was later revealed that Vivian had survived the attack with some assistance and rejoined the ongoing narrative.
1 Villain: Claiming Margaret's Body
Ludociel's offer to Margaret was not entirely an act of charity. It came under the condition that he would be able to possess her body henceforth, using it as a vessel to enact his war against the Ten Commandments. When her father, the King of Liones, pleaded with him in order to restore her to how she was, he obstinately refused.
This was in spite of the fact whoever's body contains an Archangel is destined to age rapidly. Such a phenomenon was observed through Sariel's possession of his host (as Tarmiel had animated a corpse).