Hi all - I have done a comparison of Bound Aegis and Hardened Ward. If there are errors in my math or calculations please do not hesitate to correct me.
I have used data from UESP (Thank you for your help!).
Bound Aegis
Protect yourself with the power of Oblivion creating a suit of Daedric mail that increases you block mitigation by 36% for 3 seconds. While slotted, your Max Magicka is increased by 8% and you gain Minor Ward and Minor Resolve.
Hardened Ward
Conjure globes of Daedric energy for protection, granting a damage shield for you and your pets that absorbs xxx damage for 6 seconds. Your own globe absorbs 23% additional damage. Damage shield strength capped at 50% of your Maximum Health.
Test Character Stats
Imperial Sorc
28,713 Health
All passives unlocked
Capped resistances
Around 450 CP
The main assumption with the Bound Aegis skill is that it is to be used by tanks in order to mitigate hard hits in PVE. I would like to show you all that in fact Bound Aegis is a waste of magicka unless you are wanting it for the 8% increased magicka.
Mitigation
Base: 60.5%
Blocking: 84.20%
Blocking w/Bound Aegis: 91.30%
Hardened Ward Damage Shield Value: 13477 (tooltip, no points in bastion)
Scenario: 100,000 damage hit to be mitigated
Not Blocking: 100,000 - (100,000 * 60.5%) = 39,500 DEAD TANK
Blocking: 100,000 - (100,000 * 84.2%) = 15,800 damage to health
Blocking w/Aegis: 100,000 - (100,000 * 91.3%) = 8,700 damage to health
Blocking with Hardened Ward: 100,000-(100,000 * 60.5%) = 39,500 - 13,477 (Dmg Shield) = 26,023 - (26023 * 84.2%) = 4,111 damage to health after shield & blocking
Now let's look at the skills.
With Imperial cost reduction plus other passives, Hardened Ward costs 3230 Magicka and lasts 6 seconds.
With Imperial cost reduction plus other passives, Bound Aegis costs 3726 Magicka and lasts 3 seconds.
The calculations have taken into account the minor ward and minor resolve. In fact we do not care because we were already at cap.
The question now is, why would you ever want to slot or run Bound Aegis unless you want the 8% magicka? This skill is supposed to be used for tanks but as I have shown here, you are better off casting hardened ward than ever using this skill. Hardened Ward + Block is giving 47% better mitigation. Also, the increased cost for Bound Aegis as well as the short duration (3 seconds) makes no sense whatsoever.
I would like to state that I might be wrong in that I am not sure if damage shields also have CP applied to them such as direct damage reduction, physical damage reduction, etc. If damage shields utilize CP in this manner, then they will greatly outperform Bound Aegis.
Thank you