Iron Heroes (originally from Malhavoc Press, now from Fiery Dragon Press) has ‘mastery feats’, groups of related feats that can only be accessed by characters with particular ‘mastery levels’ of a sort suitable for the feats.
Classes provide different progression rates in the different masteries. Some might focus on “Power mastery” (feats that depend on strength and large weapons and striking hard), others on “Finesse mastery” (feats that depend on precision and quickness and cause multiple minor wounds or small but vicious wounds). A character’s ‘best mastery’ will likely be equal to about one-half his level, ‘secondary masteries’ might be a third, and others a quarter or less.
Each mastery feat set has a specific gateway feat that must be taken, then others can be taken freely when feat slots are available as long as the relevant mastery is high enough.
Each mastery typically has one or two feats that could reasonably be put in a single tier. Where a mastery has only one feat it is pretty simple, just create a talent that has one feat per tier. Where a mastery has two feats I could go with paired talents, each providing one of the feats per tier, and possibly have a prerequisite between them, but I think for now I will simply have each tier provide all feats that would fit the level of the tier.
That is, Expert tier will have any Mastery 1 and Mastery 2 feats, Heroic will have any Mastery 3 and Mastery 4 feats, Master will have any Mastery 5 and Mastery 6 feats, Champion will have any Master 7 and Mastery 8 feats, and Legendary will have any Mastery 9 and Mastery 10 feats.
It is possible there will be gaps or tiers that need improvement and adjustment. That will come later, for now I will be satisfied with creating something to improve and adjust.
Iron Heroes class abilities will be in another section (or another document; this one has 45 talents in it already!) to come later.
IH is pretty well thought out, and aims to make fighters more awesome, so it seems pretty safe to include them. It seems like it’s going to take you a lot of work to adapt from D&D mechanics and terminology to Echelon20, but perhaps that’s less important than getting a playtestable version up. You can pick a gaming group that won’t be fussed (much) by any mismatch.