More items could be interesting. I think they have the alternate gold items pretty good, but other items don't have decent counterparts. Right now it can be pretty tough to justify not getting Ardent Censor for a person that heals/shields. Perhaps a different one that buffs Resistances or Attack Damage instead of Attack Speed. Different options allow different strategies.
Also there is no real reason to upgrade the Sight Stone to a Ruby. A different upgrade like say, combine Sight Stone with Warden's Mail to make a Vest of Clarity (2100gp perhaps?) that grants 200HP, 60Armor, 15% reduced attack speed and 5 ward charges. This would give an alternative to Frozen Heart, though it doesn't have the CDR or as much Armor. The big savings here though is that it upgrades your Sight Stone for part of another item you were probably going to build if you had the cash.
Another item that could use an alternative is Mikael's Crucible. As Leona, I have never had an issue with her mana well, so picking up Chalice to build the Crucible seems an utter waste. I end up going for Aegis which builds to Locket or Banner instead. And the promote from Banner while interesting does not outweigh the benefits of the shield Locket provides in team fights.
But getting back to topic, Crucible has an active that removes all debuffs on a target that honestly is going to die in the next second anyways (the 150+10% heal doesn't seem to spare anyone). I was thinking an item that swaps positions and removes debuffs would be vastly superior for a Tank support that arrived a little late to a fight or somehow got kited around (or the squishies got ambushed from behind due to improper warding, etc.)
I'd put it up there with Banner and Locket in price, since it would be so much better than Crucible. The active would be a position swap that removes your allies debuffs but does not provide the healing Crucible does. But first, I think we need to add an Advanced Item to its build that imitates Aegis.
Ancient Hauberk - 1700gp 200 Health / 20 Armor Unique Passive – HARDENED: Nearby allied champions gain +20 Armor and +50% health regen per 5 seconds. (1100 range)
Build is Identical to Aegis though Null Mantle is replaced with Cloth Armor.
Adding Bami's Cinder instead of Kindlegem
Martyr's Gate - 3000gp 550 Health / 25 Armor Unique Passive – HARDENED: Nearby allied champions gain +20 Armor and +50% health regen per 5 seconds. (1100 range) ; Unique Passive – IMMOLATE: Deals 5 (+1 per champion level) magic damage per second to nearby enemies. Deals 50% bonus damage to minions and monsters. Unique Active – Removes all stuns, roots, taunts, fears, silences and slows on an allied champion and swaps their position with yours (180 second cooldown).
Anyways, just some ideas that probably would break the game in coding.