The inconsistency of armor buff abilities in ESO in conjunction with their cost has been a long-standing issue in ESO. Some classes have strong, useful armor buff spells and others have a hard time justifying even slotting it. The wildly varying nature of these spells' durations are also an issue given the fact that the spells themselves are rather costly for being a simple utility spell.

The current live values for armor buffs in ESO:
Based on what we can see here, it is evident that cost does NOT correlate to more powerful effects or even a longer duration. The Templar's defense buff is only armor buff that is properly balanced with cost, duration, and potency. All other classes need adjustment (buff) to make their buffs cost less and/or do more:

Sorcerer:
- Adjust both durations up to 20 seconds, with their DoT damage adjusted to account for the duration changes.
- Halve the resource cost for both morphs.

Dragonknight:
- Increase Volatile Armor's damage reflection and the AoE DoT damage.
- Increase the damage shield on Hardened Armor and grant additional 12% healing received while active.
- Replace Burning Heart's healing received passive with an execute passive that scales DoT damage on enemies below 50% health.
- Halve the resource cost for both morphs.

Nightblade:
- Increase the base duration of the armor buff to 12 seconds. (A 1-H DPS setup gets 15 seconds and 7-H tanks (who do not spam shadow spells) can get 33 seconds.)

Warden:
- Adjust the duration to 20 seconds for both morphs.
- Decrease the resource cost significantly for both morphs, putting it in line with other classes.

Necromancer:
- Summoner's Armor will instead regenerate an additional 200 magicka and stamina each time you consume a corpse while the armor buff is active.
- You can now recast Beckoning Armor (while it's active) for half cost while targeting an enemy to pull it to you. (Subject to CC immunity ofc.)
- Halve the resource cost of both morphs.