In the Seven Deadly Sins anime, much of the plot revolves around the kingdom of Liones. It is one of the most resilient bastions of human life, withstanding numerous invasions from demonic adversaries and the home of the finest Holy Knights in all of Britannia.
Like any nation, Liones is imperfect. It has succumbed to corruption on more than one occasion, whether through gullibility or desperation. By acknowledging the worst crimes of the kingdom and through comparing them to their greatest accolades, we can assess whether or not they are a nation worthy of the Seven Deadly Sins's protection.
10 Crime - Hunting The Sins
Under the sway of the Grandmaster Hendrickson, the Holy Knights scoured the kingdom in search of the Seven Deadly Sins. Despite how they had faithfully served in previous wars, they were wanted for treason against the realm that they never actually committed.
This was through the machinations of Fraudrin, who had been possessing Hendrickson's body. Once he had been beaten, the tension between the Sins and Liones was eased, though it would not excuse the lengths they went to in attempting to defeat Meliodas.
9 Great - Standing Up To Hendrickson
When Grandmaster Dreyfus finally realized the truth behind Hendrickson's deception, he confronted him personally despite the latter being infused with the power of the Ten Commandments. It resulted in a heroic clash, though one which would, unfortunately, result in the red knight's defeat.
Nonetheless, it displayed Dreyfus's integrity and that he was willing to own up to his mistakes. Should he have attempted to destroy the Sins regardless to maintain a strong appearance, it would have been much more difficult for Meliodas's group to have prevailed.
8 Crime - Torturing Ban
Despite his incredible skill, Ban was captured by the Holy Knights and held within one of their fortresses. They attempted to execute him through numerous means, though because he was immortal, none of them succeeded.
Regardless, they were willing to torture an innocent man to death, one who would later become their savior. Jericho was especially interested in his humiliation, only for her malice to later give way to infatuation the better they got to know one another. Unfortunately for the Holy Knight, Elaine was not thrilled by this and would attack as a result.
7 Great - Attacking Estarossa
When the Ten Commandments returned for their brutal reckoning with Britannia, few could stand in their way. Even the combined might of Archangels Sariel and Tarmiel could not oppose him despite their legendary strength.
Regardless, Howzer leads the charge against this impossibly daunting villain despite the fact that he would not have been much of a match even before Estarossa absorbed the strength of his allies. Through their courage and gallantry, they prevented him from executing Guila. He was even able to bombard the demon with such commendable force that he made him stagger, a feat worthy of Escanor's admiration.
6 Crime - Drinking Demon Blood
After being defeated handily by Meliodas and his friends, it was becoming increasingly evident to the Holy Knights that they did not stand a chance against him on their own merits. Hendrickson proposed a solution ~ the "worthiest" among them would imbibe demon blood, transforming them into the most powerful weapons the kingdom had to offer.
While it did indeed grant them power, it also mutated their bodies into gurgling monstrosities and robbed them of their personal autonomy. Many of the knights (such as Twigo), would not survive the transformation, perishing before their newfound strength could see battle.
5 Great - Hendrickson Joining Meliodias's Quest
When Hendrickson was finally restored, he knew that an apology wasn't enough. The Grandmaster aided the Sins' quest as much as he was able, including witnessing the return of the Captain's full power.
Though Ban and the others may have harbored reasonable misgivings against him, he earned their trust through his loyalty and competence. By the time Estarossa cut Meliodas down, he would mourn alongside them as friends, demonstrating the fealty he felt for the man he had previously attempted to murder.
4 Crime - Ganging Up On Diane
Though Dreyfus would later prove a worthy ally to the Sins, he was a completely remorseless enemy. When he had cornered Diane alongside Gilthunder and Howzer, he was determined to take her out, coaxing the latter to turn his wind on her even though he knew she was not guilty.
The result left the giantess a battered and beaten mess, unable to thwart her attackers even with the power of her sacred treasure. It would result in one of the Holy Knights' most significant victories ~ even if it was in the service of evil.
3 Great - Bartra's Blessing
Elizabeth may have been the reincarnation of Meliodas's beloved "Liz," but she was also the daughter of Bartra Liones, ruler of the kingdom which shares his namesake. This made her continued adventures with the group much more difficult since her father did not approve of the dangers she would partake in.
Nonetheless, when the captain came to collect her and she joined his side, Bartra would not send his knights to pursue them. Ultimately, her assistance would be invaluable to the team, especially as a fantastic healer.
2 Crime - Aligning With Ludociel
Superficially, it is understandable to see Ludociel's appeal. He offered to balance the disparity in strength between the humans and demons, even promising to eradicate them from the face of the planet.
However, when others would publicly question him about his motives, he put them under the sway of "Fraudulent Light," a spell which guaranteed they would die for the Archangels. Though some would continue to be suspicious of him, Hendrickson would offer his full support to his new ally, even though he had already been manipulated by supernatural powers before.
1 Great - Defending Diane
Though Guila and Howzer played a role in Diane's defeat, they would not allow Dreyfus and his minions to finish her off once they had made their intentions clear. Despite the risk to their careers, reputation, and even lives, the two Holy Knights stood up against their superiors to do what they knew to be right.
Because of the destruction the battle caused, it attracted the attention of Gowther, who was then able to save the giant from certain death. Without the knights' honor, the Seven Deadly Sins would be short a member, and their relationship with Liones would have never been the same.