Looking up the wiki (H&H may have changed these values, like with bows maybe), it looks like this is what you get at 100 skill:

Running+25% Run speed -50% stamina usage. This one seems pretty good. Combine it with the Eikthyr buff and you can Run Forrest all over the map. Its also one of those skills that is pretty much always steadily increasing, and thus I would assume the highest stat most players will have at any given time.

Jumping +40% Jump force. The term 'force' here suggests its not just raw vertical jump height that improves, so when sprinting I'd assume much greater horizontal distance you can cover. Notable here is that the stamina cost of jumping doesn't go down however, so unlike improving the Run skill improving Jumping doesn't necessarily make it more efficient. While I like to jump to hop out of harms way, as a matter of practicality being able to jump more frequently is more relevant than being able to jump a bit higher/further. Its what I like about the Eikthyr buff as well, particularly since you'll get access to that buff at a point when your run/jump is still pretty garbage.

Sneak -60% initial sneak visibility, -20% light based visibility and -75% stamina usage. So this one gives you a lot, and hitting unaware enemies is a nice burst. The reduced stamina is significant compared to what you get for other skills, but sneaking means you are moving slowly. I'm not sure how practical this strategy is overall; in theory you could have the Troll Leather set to ambush enemies and hopefully one shot them. But I can do that with a bow from far away without having to rely too hard on subtlety anyway, so why would I risk getting right up behind them to stab them in the neck instead?

Blocking +50% block power. I imagine this could stack up nicely with the higher tier tower shields to be able to just mitigate hits outright. Though it is too bad it doesn't contribute anything to parrying or the stamina cost of blocking itself. If the skill only went up based on just the flat # of blocks then it also seems like it would take ages to max it out.

Swim -50% stamina usage. Swimming is slow and takes much longer to get anywhere, and you take damage in deep water at 0 stamina so it feels tedious to level it up to a significant amount. Half stamina/second is nice but thats at 100 swimming when in practice most people are going to have a fraction of that. I also don't understand why you wouldn't at least make it faster like with running since the default swim speed is extremely slow. Even with less stamina drain, it means swampy areas are still a liability because the water will slow you down just as much regardless.

Mining and Woodcutting +150% vs material (mining says also -33% stamina use, I'm assuming woodcutting also gets this via axes?). Not super important, just a convenient reduction in time and stamina spent whacking away at resources.

Bows 150% damage and (used to be) -100% draw time. Apparently nerfed in the last update wrt draw time but I can't recall the exact value now. When you factor that the stamina use is directly tied to the amount of time drawing the bow the reduction in draw time, even if its less, is still significant. With a slower draw bows are mainly used for the initial shot but with faster draw you can be much more aggressive with them. I would assume people spend much of their time pelting bosses with arrows, which makes this skill quite relevant. In testing now, I observed a HUGE difference from 0 to 100 bow skill even after the update.

All other weapons +150% damage and -33% stamina drain. The combination of damage and stamina reduction make your typical 3 hit combo much more efficient; you'll get more hits off before running out of stamina. Even at 30 weapon skill (not super difficult to obtain) you're theoretically looking at 50% damage -10% stamina use which is nice. While I know its EA and the values might change, the uniformity of the bonus across different weapon types does give me pause. It will typically motivate players to focus on the most DPS efficient weapon type since maxing out a suboptimal weapon type won't be worth it in the long run (aside from just being for fun, of course :) ) . In the future, I do hope we see more unique improvements to different weapons to encourage players to experiment and build up many different weapon skills since at the high end they will offer more unique experiences.

So how do you feel about the skills in the game? Fair? Too good? Is losing 5% of your stats each death fair? I know there are going to be the 'git good' and people that can scramble around Valheim for hundreds of hours as a naked caveman without dying. But realistically the penalty should be harsh enough to motivate players to be careful/fight smart yet not so punishing it discourages people from trying or burns them out. One thing I did notice in this regard is that it takes progressively more effort to make skills go up, which means the higher they were when you died the more time you lost in the process. Is it expected that an average player will be motivated to try to max out stats even if they do die frequently in the game? Even if you're not Leeroy Jenkins careless you're going to have "Valheim moments" (falling trees ) sometimes.

Also, in testing, how do you feel your Einherjar performs at, say, 0/25/50/75/100 skill overall? Even with linear improvements, there will be 'jumps' in progression (if you become just strong enough to kill a particular enemy in 1 less hit then your survivability improves quite a bit more than a fraction of a percent). On the other hand, if the values themselves are still negligible then it kills the motivation to work towards building that skill up for all but the most obsessed minmaxers.