Norsca is the only faction right now with only 2 legendary lords with the edition of so heres my idea for a new one plus some additions/ changes to the faction as a whole.
For starters the changes/additions. At the start of a norsca campaign you can choose to follow chaos or not, or rather wulfrik can since trolls are chaos creatures so throgg can only go chaos and the new legendary lord will be anti chaos. this decision will change certain building and campaign mechanics. Skin wolves, trolls, manticores, and fimir are chaos creatures so if you go anti chaos these will be replaced with einherjar (spirits of norscan ancestors), norscan dwarves, giant dire wolf, and half giants. originally norsca razes settlements to one of the four chaos gods, khorne, tzeentch, slanesh, and nurgle or the hound, the eagle, the snake, and the crow. if you pick anti chaos they are replaced with ulric, taal, manann, and rhya. their symbols should be a wolf, stag, albatross, and tree. unlike the chaos gods who are rivals these gods are a family so worshiping one doesnt take points away from the other, although you can still only get to tier 3 with one faction.
the allegiance to the gods rewards are a bit different if you go anti chaos, the wolf would be the same as the hound up to tier 3 where instead of the ice forged legion you get some type of special dwarf canon. the stag would be the same as the eagle until tier 3 where azrik the maze keeper is replaced with styrmir rimefrost (picked this guy since if you go anti chaos you cant confederate who is the king of the frost giants. the albatross would be the same as the serpent up to tier 3 where kihar the tormentor is replaced with the ravenswyrd chosen of the gods. for the tree instead of a plague at tier 3 you get a large buff to growth and public order.
while you can only raze settlements besides certain capitals and ports you can now capture all capitols of a province and turn non port towns into farms that provide income, plus taking ports and making farms is used for manann and rhya instead of razing settlements (more specificly building temples to manann and rhya in ports and farms. the settlement capitols should have some structure that decreases recruitment time for local and global recruitment. the einherjar function like tomb king units in that they dont cost money but only a certain amount can be built depending on how many structures you have (im thinking a shrine to the ancestors) and the hero unit would be an einherjar chief or lone warrior. the fimir and fimir balefiend replaced by norscan dwarf warriors (or longbeards depends on which is closer to stats of fimir) and runesmith.
Now for the stuff that effects all norscans. Monstrum Arcana stays but we add one more hunt that gives access to a different hero depending on if you go chaos or anti chaos. it ends with a three way battle with you and your sides hero, the creature your hunting, and the other hero and their forces. anti chaos hero is jora and bjorn, a bear man and warrior woman. we got a double legendary lord with twisted and twilight and we got quest specific heroes in the hunter and the beast so they are plausible. and chaos gets melekh the changer. new lord type the vikti aka lord version of shamans. new units, shield maiden basically marauders with missile defense and higher leadership then marauders since they are usually called out to defend the home so they should have higher leadership then the normal troops, marauder archers (marauder hunter is taken so its either marauder archers or marauder hunters (bow and arrow)) should probably have vanguard deployment, and marauder wolf riders which should be the shock cavalry since norsca doesnt really have anything that fills that role. norsicans are supposed to be some of the best sailors in this world so an increase in campaign movement distance when on the water for all lords either inherently or in the blue line and wulfrik should have the most since hes got a magical longship. the provinces need to have comandments.
The legendary lord should be a valkyre, who is against chaos, coming from either the Bjornling or the Skaeling tribes as those are the most distant from the forces of chaos and only do the raiding when necessary. we know we can have foot lords with wings on their back because we got malaghor from the beastmen running around so thats not an issue. this lord would probably be a hybird melee/spellcaster with lore of light, death, or beasts. she will give bonuses to ancestor spirits, wolves, and shield maidens. (if GW doesnt let you make a legendary lord then just go through the list of famous norsicans and pick the least chaos one and use this or something like it as the unique lord or hero from one of the gods or not at all). the new legendary lord should also have special missions they can undertake to prove they arent aligned with chaos to increase their reputation with specific "good" factions.
the list of links to the sources i looked through for this.http://warhammerarmiesproject.blogspot.com/2013/04/warhammer-norse-proper-8th-ed-out-now.htmlhttps://drive.google.com/file/d/0B_Redi9cZJ5iUnRkYmR6V1YxNFk/viewhttps://warhammerfantasy.fandom.com/wiki/Old_World_Pantheonhttps://warhammerfantasy.fandom.com/wiki/Taalhttps://warhammerfantasy.fandom.com/wiki/Rhyahttps://warhammerfantasy.fandom.com/wiki/Manannhttps://warhammerfantasy.fandom.com/wiki/Ulrichttps://forums.totalwar.com/discussion/190768/norsca-army-list-from-official-sourceshttps://warhammerfantasy.fandom.com/wiki/Norscahttps://totalwarwarhammer.gamepedia.com/Norscahttps://totalwarwarhammer.gamepedia.com/Dwarfs_unit_rosterhttps://totalwarwarhammer.gamepedia.com/Allegiance_to_the_Gods