If anything we should nerf all the lower abilities so that they match up with a natural progression which leads up to t6 being the best.
Like take cloaks for example. The t6 gives 5.5 invisibility and 4 dex, 5 spd, 2 vit, 2 wis, while the t5 gives 5.5 invisibility and 4 dex 4 spd. It would be most reasonable to simply take off .5s of invisibility from every ability below it and just remove all wis and vit stats and 4 dex on the t5 cloak. So the progression would be like this:
Cloak of Shadows
60 MP
2.5 s
Cloak of Darkness
65 MP
3s
Cloak of Speed
70 MP
3.5s
+1 SPD
Cloak of the Night Thief
75 MP
4s
+2 SPD
1%
45
Cloak of the Red Agent
80 MP
4.5s
+3 SPD
Cloak of Endless Twilight
85 MP
5s
+4 SPD
Cloak of Ghostly Concealment
85 MP
5.5s
+5 DEX
+5 SPD
This could also lead to some more unique aspects of the UTs since the invisibility times and stats of the tiered items would be slightly different. For example:
UT
Cloak of the Planewalker
90 MP
5.5
Teleports
+7 SPD
+3 DEX
6%
750
You also mentioned helms where it would also make sense to nerf every helm below the t6 one. It would probably look something like this:
Combat Helm
50 MP
6 range
3s
Bronze Helm
65 MP
6 range
3.5 seconds
+1 DEF
Black Iron Helm
70 MP
6 range
4s
+2 DEF
Red Iron Helm
75 MP
5 Range
4.5 s
+4 DEF
Steel Helm
80 MP
5 Range
5s
+6 DEF
Golden Helm
85 MP
5 range
5.5 s
+8 DEF
Helm of the Great General
85 MP
4 range
6s
+10 DEF
These abilities would need to be changed:
Quivers(who’d want to pay an extra life for +2 Wis and +2 VIT on an archer)
Spells (To some degree. I don’t like how the t6 and t5 have the same average damaged)
Tomes(Speedy is unoriginal and doesn’t make for much sense on a tiered tome)
Poison(How the hell does t5 do more damage than t6???)
Traps(T5 too similar to T6 imo)
Prisms(Lol who even uses t6 prisms)
Some of course don’t really need to be changed. Like shields and orbs. Scepters for example, are fine as is pretty much. They have a good/logical progression.
Just an idea of course.