I am not sure if you accept suggestions but...

Some skills related to Health & Hunger.

Skill 1 - Vitality
Increases maximum Health. Each Level adds 2 Health, up to a max of 20 at Level 10.

Skill 2 - Stamina | Requires Vitality.
Lessens Exhaustion Build-Up for running, jumping, attacking mobs, and from the Hunger Potion Effect. Each Level adds 5%, up to a 50% reduction at Level 10.

Note
For Health it's best to use an attribute modifier otherwise conflicts will occur with certian mods, like Scaling Health. For Exhaustion... I dunno if this would work with mods that adds in exhaustion build-ups of their own unless maybe levelup detects the exhaustion value and then lowers it?

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Now for some damage reduction, even though there is an overall damage reduction skill aka 'Iron Skin' but what if starting with reducing damage from sources that Armor affects before you're able to reduce the damage taken overall?

Skill 3 - Fortitude
Increases your Armor Points. Each level will increase your Armor by 2 points, up to a max of 20 at Level 10.

Skill 4 - Endurance | Requires Fortitude
Increases your Toughness Points. Each level will increase your Toughness by 2 points, up to a max of 20 at Level 10.

The 'Iron Skin' skill will require 'Fortitude' before you can increase it.

Note
I was going to say 1 point but I think you have the max level cap set at 10 Levels by default, at least by looking at some of the .json files, so I went with 2 per level. Also can use attribute modifiers for them.

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Something for Melee & Range, in a way.

Skill 5 - Precision Aim
Improves your aim, adding a chance to deal Critical Damage. Would be the same as the 'Random Crits' skill where you can deal 2x the damage, only this one is for range. Max Level is 5 with +5% per level, up to +25%.

Skill 6 - Sword Speed
Improves your Attack Speed with tools. Would be just like the 'Archery' Skill only... this one is for melee. Max Level is 10 but I am unsure of the increase as Archery doesn't list the value.

P.S.
If there could be some form of scaling the values, like say with Random Crits capping out at 25% and there's 5 levels... perhaps we could set a max value with each level adding x amount per level, for example... if I increase the level cap to 10 but keep it at 25% | 0.25... the skill will add +2.5% per level.