I feel that the items don’t really serve a purpose of helping martial vs caster issues. You may as well just hand out more potions and raise their level cap.
For the martial/caster issue, I have an alternate rule, where spells “known” is limited by a formula to slow the entrance of problem spells. For 9 spell level classes you can only learn spells of level 1+(character level)/3. For 6 spell level classes you are limited to 1+(character level)/4. Slots for spells known and per day are still gained at the usual levels, but must be filled with metamagic or lower level spells. Other class abilities that mimic spellcasting also need to be similarly effected, like the summoner’s summon monster ability.
This rule doesn’t begin to effect casters until the levels where martial vs caster issues begin to become a thing. And it basically removes level 8 and 9 spells from the game. It also makes multiclassing a caster more attractive, as you aren’t missing out on higher level spells as much.
My goal wasn't to address caster/marital disparity as that isn't much of an issue at my table. What I was interested in was to balance the items with each other.