Is the +10 skill affix the max you can get? Isn’t there any +15 or +20?
You can get +20 single skills with some specific eternal legendaries.
Only +10 all skills with mythic stone on your weapons .
Oh thats bad. Since you cant use quartz on eternal items, right?
Eternal items are far too limited due to inability to craft.
However, Eternals are also very intriguing since you could get lucky and end up with a piece that has all the right affixes and perfectly rolled stats.
If your build only uses one Skill to do all your damage, you put 20 Hero Points into the Skill and two +10 Skill on the Build to get the +40 Skill Points.
If you find an Eternal Item that has a +20 Skill you need, and all of the other affixes work with your Build, you can go that way.
If your Build will use 2 or more Skills, or a lot of Proc affixes, you could use the two +5 All Skills (affects all weapon skills used, including Procs) and any +10 Skills as needed.
there are also many builds that only have their Weapon Skills at +20 to save space for other affixes.
here’s a post showing the few Crystals that can be used on Eternal Items.