Meliodas's son, Tristan, is incredibly powerful as a Nephilim (Demon/Goddess hybrid), inheriting Full Counter, Dark Magic, Divine Light (Ark), and immense physical strength, with potential to surpass even his father, capable of wielding demon and goddess powers simultaneously, although his full capabilities are still developing and hindered by amnesia. He wields both demonic and divine swords, making him a formidable dual-wielder with immense potential to become a hero greater than the Seven Deadly Sins.
He is also shown to have inherited Goddess powers from his mother and Demon powers from his father, which he can manifest either separately or simultaneously. Having the blood of a high-ranking demon, Tristan can survive the most fatal injuries such as his body being split in two.
Eventually, after unleashing his Life Spirit double, he is able to beat level 1-4 of Lancelot's fighting ability. This included replicas of Pellegard and Ironside. The only version Percival cannot beat is level five, which is Lancelot himself.
While he rarely fights, the Demon King possesses unparalleled might in battle even after having delivered half of his power, with Meliodas himself said that he was utterly powerless before his father and was killed effortlessly by him in the Holy War.
Zeldris「ゼルドリス」 is the current king of the Demon Clan, the lover of the Vampire, Gelda, the younger brother of Meliodas, the surrogate father to Percival and the youngest son of the previous Demon King.
The Demon King cries that if the attack hits him again, Britannia will be damaged. However, Meliodas still sends the attack to the Demon King, defeating him once and for all.
However, the Demon King and the Heavenly Goddess cursed them both— Meliodas was cursed with immortality while Elizabeth was cursed to be reborn over and over again. Each time she's reborn, she wouldn't remember her previous lives but eventually she would, and when she does she's bound to die in 3 days.
Tristan states that after his disappearance, Lancelot's power had increased until it completely exceeded his own, allowing him to match the Seven Deadly Sins.
However, Meliodas sacrificed his godly power to cancel out the Commandments in order to prevent his father from ever returning again and thus lost his new power and was able to remain in Britannia once again.
After Howzer defeats the Ancient Dragon, Donny refuses to continue carrying the Dragon Handle because it would mean that Camelot's forces would pursue him, so Percival decides to charge it in his place. Howzer then repairs its blade to turn it into Percival's sword.
In this epic comparison, while a current Meliodas may not be able to defeat Arthur due to the absence of his True Magic, the potential gives him an edge.
Gawain「ガウェイン」 is one of the Four Knights of the Apocalypse, the daughter of Escanor and Merlin, and the adoptive niece of Arthur Pendragon of Camelot.
Tristan can also use Full Counter, thanks to his father's teachings, but initially seems unable to master it as well, earning him the nickname "Foul Counter"「ボロカウンター, Boro Kauntā」. However, over the years, Tristan becomes capable of using Full Counter as well as his father.
In my opinion he is probably the second strongest after Meliodas (obviously with the regeneration powers). Meliodas is stronger than the demon king. Ban is a little weaker than the demon king.
Guinevere is a mysterious but very bold girl, having no problems being assertive and forthright about her desires, calling Lancelot her lover and kissing him.
Arthur was grateful for his aid and later made him a Knight of Camelot after he volunteered to help rescue Uther (The Coming of Arthur). Lancelot sacrificed himself in Arthur's place to banish the Dorocha, leaving Arthur deeply saddened.
Meliodas and Zeldris should definitely have a lifespan of more than 1000 years ESPECIALLY as the children of the Demon King. edit: and in Meliodas' case he's going to outlive even Zeldris considering he's been alive for 3000 years he just hasn't aged.
Meliodas' first wife, Elizabeth, who bore the hero Tristan, was Mark's sister, and his second wife was a daughter or sister of Hoel of Brittany. He is the eponymous protagonist of the romance Meliadus. The Italian variant Tristano Riccardiano calls him Felix (Felissi).
It's simple, Meliodas is functioning at like 1% of his total power, rest of it has been sealed. Also Meliodas has a crippling problem of never getting serious in fights.
After going to Purgatory, he lost his Immortality.
Zeldris recalls what Meliodas told him when he convinced him to help him become the Demon King: that Gelda is still alive, and how he re-sealed her twelve years ago when she wanted to die.
While she rarely fights, the Supreme Deity's might in battle is terrifying, as evidenced by her ability to easily overpower and kill Meliodas in the Holy War of which Meliodas claims that he was utterly powerless to fight back against Elizabeth's mother.