So I know the Runecarver gives you quests to get your recipes for making legendary base items like the Umbrahide Pauldrons for examples, but how do you get the upgrades to go from 190 to 210 to make them higher ilvl? This is for profession crafting by the way not for making an actual legendary item out of soul ash.
You have to repeatedly craft the item in question. As you do you gain xp that will allow you to make the higher ILVL version.
Rank 1 Base Items (Item Level 190) give 5 XP per crafted item and the Total XP you need to unlock Rank 2 is 75, meaning you must craft 15 Rank 1 Base Items to gain access to Rank 2.
So farm tons of mats. Got it.
Just buy the base items at this point. It costs much more to level the base items than to buy them.