Don't be fooled by the nice appearance - this guy is pure evil, and a colossal asshole.

"Sometimes, I look out at nature and I think, 'Everything here is obeying my conjecture.' It's a wonderfully narcissistic feeling."

– Geoffrey West

"Sickly, sinful, spectacles stand, shuffle, shamble and saunter shamelessly in mine scandalized sight! I suggest a solution... Surely such sedition should sour and succumb to Sigvald - the salacious, scandalous and sensational servant of Slaanesh! Son of Succubi, scion of sordid acts and slayer of squalid serfs!
See how I stroll, stride, swagger and swirl, spin, and slash and stab at stupid, senseless scum! Soon they shall swoon, shall seek solace and death from sundry and torments wrought on them by my strategic, severing, scintillating shower of shimmering strikes!
Send for the sword - summon Sliverslash!

– Sigvald the Magnificent, alliterating like a boss during the Sliverslash quest battle

Imagine Joffrey Baratheon growing up, and gaining the favor of the god(dess) of being a colossal narcissistic asshole FOR being a colossal narcissistic asshole, along with getting demigod powers and an army of sick fucks. That's who's the Sigvald is. He's also a pithy wordsmith. (Magnifissscchent!)

Sigvald was born from an incestuous relationship between a powerful warlord and his sister. Sigvald was beautiful from birth, save for a horned birthmark on the back of his neck, and was spoiled by his father until expelled from his tribe by his father due to his "fondness for human flesh". Sigvald proceeded to murder his father in his sleep and departed for the Chaos Wastes, earning Slaanesh as his patron. Now, Sigvald marches at the head of an army devoted to himself, eradicating anyone he deems to be ugly, crude or irritating.

Sigvald has burned down cities on a whim; one story suggests that he destroyed the town of Chamburg because the wine there was not to his taste. Other exploits include declaring war on a province of the Empire because he once broke a nail on a warrior priest's armor during a previous battle and heading to Ulthuan to scalp as many High Elves as he could because their hair was prettier than his/they were more renowned for pretty hair than he was.

He is spoiled by Slaanesh and is described as being extremely self-centered: his body-guards bear mirrored shields so that he may preen himself in the midst of battle. His gifts from Slaanesh have left him beautiful on the outside, but rotten inside. The ground literally reshapes itself for him and his feet float an inch above the world's surface. He wears an armor of ensorcelled gold that never rusts or gets dirty and fights with Silverslash: a rapier of silver forged from the sword of Slaanesh.

He appears a few times in the end times, first ravaging Kislev. After this he makes his way to Bretonnia where he heads the siege of Parravon. His forces overwhelm the Grail Knights and forcing Gilles to retreat, but not before he kills Sigvald's right hand man. Chaos Joffrey then goes on to take a break from fighting and turns Parravon into his own personal paradise, feasting on the finest flesh Bretonnia has to offer. Much to his dismay, the Chaos Gods pick him up and put him in Middenheim, where he is one of the few chaos champions worth a name still living. He throws a hissy fit about not having his mirror eunuchs, and offers Mannfred a spot as a replacement. He was one of the warriors tasked with killing Valten before he reached Archaon, alongside Valnir and Wulfrik, but lounges on the stairs preening himself while the other 2 duel. He makes an excuse that he doesn't want to fight Valten because he deserves to fight the real Sigmar, and prances off to parts unknown.

He is still alive during the final battle, leading forces of daemonettes against Nagash's army. Archaon had ordered him to fight alongside the troll king Throgg, a prospect that horrified Sigvald due to Throgg's hideous appearance (with Throgg teasing Sigvald over his foppishness and squeamishness). So he tried to kill Throgg and split their forces up. Sigvald fought Krell in a badass battle, and was doing badly at first since Krell is stronger (despite Sigvald being S5 while Krell is S4, though Krell's axe gives him +2S, never mind) and more durable. Then Krell cut his pretty face and broke his sword. Sigvald saw his reflection with the one eye Krell didn't ruin and went absolutely berserk, beating Krell down with his bare fists and mangling his perfect hands in the process. After stabbing Krell through the eye with the remains of his sword and killing him, Sigvald's rage was spent. In that moment of clarity Sigvald saw in his mirrored shield that his face was ripped to shreds and his hands were mangled to the point where he couldn't use a weapon (though Sigvald's armor meant that his injuries would heal, all Sigvald cared about was that at the present moment he wasn't pretty) While Sigvald sat next to Krell crying over his temporarily ruined beauty, Throgg approached. He had survived Sigvald's attempt on his life and he wasn't happy.

Throgg the Evertrollsen snuck up and took his revenge by smashing in Sigvald's skull with his club and pissing on Sigvald's corpse. TAKE THAT YOU SLAANESHI NARCISSIST JERK!!