Being mentally superhuman notably does not include superhumanly smart. It's more a matter of superhuman sensory perception, willpower, and the speed at which they think. Still very useful of course. At higher levels, they gain the ability to alloy together multiple Kunna (see below), creating cool meldings of those things. Norsemen are normally worse at this than Norsewomen, but again that's just a cultural standard, not enforced by anything. These abilities all fall under Hugr, the Norse word for 'mind'.
Oh, right, forgot that alloying together Kunna was a Hugr-linked thing. What's the cutoff for that again, mechanically speaking?
Because I tend to imagine Erik's practical if unimaginative spear-casts being something like Force+Spear, but I'm not sure I picture him as Hugr 7 or whatever since he's certainly not always quick-thinking.
It is worth bearing in mind that not resorting to violence when insulted can lead to nid for the insulted person, so be very careful when insulting people, as their choices tend to be nid or stabbing you. The same is true of 'shaming blows' which include attacking people with your feet, a closed fist, or an improvised weapon, and some specific tactics like groin shots...using these kinds of attacks on other Norsemen inflicts nid and thus pisses them off (note that this does not include wrestling or even palm strikes...it isn't all unarmed attacks).
Note the bit about 'improvised weapon' is culturally constructed. Thus, we imagine the Nid-afflicted and very dead soul protesting:
Poor Idiot: "Come on, man, I got killed the
fuckin' hammer of Thor, that's got to count!"
Universe: "You couldn't even get killed by a real weapon, seriously, a
hammer, lol, lmao."
Like Orthstirr but much more hardcore. None of the characters here would know much about it, not even the word, probably. Seeresses do some stuff with it.
Notably, the Norse have an ancient enemy, known generally as just the Enemy, who I think/recall is actually the mythological 'not dead which doth eternal lie' primeval giant Ymir, who is very, very good at suppressing the teaching of Odr. This is why the Norse don't use the word. Deliberate Odr cultivation ("True Norse cultivation") is quite powerful, but also spectacularly dangerous if you fuck it up, and you have to figure it out for yourself because as soon as any other Odr cultivator tries to talk about it, the Enemy hears you and starts pulling a mix of monster attacks and reality-warping shenanigans to destroy you.
As an example of just what lengths the Enemy will go to, we are all refugees from the island of Gotland, which sank into the sea as a result of a battle between Hallr Blackhand and the nine Steelfathers* of the i-forget-the-name Viking warband, one of the most feared forces in the Norse world. Hallr took down several of the Steelfathers because he was a badass to beyond-the-impossible levels where killing an invulnerable man was just a "skill issue, use hotter fire" thing for him, but he died in the process, and the battle sunk the quite sizeable island (OTL Gotland is about 125 by 50 kilometers).
So this was some epic clash of forces stuff that went down. And how'd it happen? Well, see, Hallr Blackhand was an Odr cultivator, and he apparently got up to some shenanigans aimed against the Enemy. And as I understand it, the Enemy just up and twisted reality so that the scariest army in all the Norselands suddenly just fucking
appeared right by Gotland and was like "oh hey we are attacking Gotland now" regardless of what they'd been doing or planning before hand.
Now, as I understand it, making this happen is pretty high-tier stuff even for the Enemy, not something he can do without effort, but even his idea of a casual slap can be pretty devastating.
So that's why the Norse don't know much about Odr. Because anyone who tries to publicize Odr gets killed by overwhelming force, and even just talking about Odr can result in the Enemy somehow altering reality so no one hears what you actually said. Scary shit.
On the other hand, since we appear to be shipwrecked in the love child of Xianxia Florida and Jurassic Park, we may be out of the Enemy's actual range. No way to find out unless someone tries to talk about Odr and does or doesn't get mobbed by every monster within a 50-mile radius, I guess!
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*(normally held to be the upper limit of badassery due to being infused with the unchanging essence of Steel and thus nearly impossible to kill)