So, I don't like the Item of Stat pattern; because it is "pure" and aimed at +X to stat, it removes a lot of possible flavour and inspiration for minor abilities.If you want to re-design the other stat-boost items you just need to pick alternative riders.
Headband of Intellect can be +2 intelligence (max 21) and the wearer gains proficiency (or expertise if already proficient) in Arcana, History, Nature, and Religion.
Pearl of Wisdom +2 (max 21) and the wearer gains advantage of Wisdom saving throws.
Cloak of Charisma +2 (max 21) and the wearer gains advantage on Charisma based skill checks.
Gloves of Dexterity +2 (max 21) and the wearer gains proficiency (or expertise) in Sleight of Hand.
Amulet of Health +2 Constitution (max 21) and the wearer gains advantage on Constitution and death saving throws. When spending hit dice to regain hp regain an additional 2 hit points.
Just spit-balling, but you get the idea.
Like, a "Sword of doing more damage" vs a "flametongue" vs a "Sword of Red Dragon's Wrath".
The primary purpose of all of them is more damage; but as you go right in that list you get more fluff in the item's identity. That extra identity makes adding flavourful features easier. And I find that makes for better itemization than "narrowly focused on optimizing one problem" items.
A Third Eye that grants +Wisdom, a Ioun's Library Link (+Int), Quickling-Skin Gloves (+Dex), or Troll-Heart Amulet (+Con).
Secondary effects (beyond the primary stat boost) now fall out a bit more naturally.