with more duration and efficiency you can worry less about mana cost now
this build can get armor up to 1248 + 900(Arcane [Guardian]) = 2148

Without Arcane [Guardian]
Armor : 1,248
Effective Hp : 5521 (90% [Adaptation] 55212)
Damage Reduce : 80.62% (with [Adaptation] [Reach] 90% you will have 98.06% Damage Reduce against that damage type)
With Arcane [Guardian]
Armor : 2,148
Effective Hp : 8731 (90% [Adaptation] 87312)
Damage Reduce : 87.75% (with [Adaptation] [Reach] 90% you will have 98.77% Damage Reduce against that damage type)

which is not that different than strength build that much
I really recommend this build

[Adaptation] rank 8 because most of my build can't get over rank 8 you can get whatever rank you want

emissive color: heat because armor reduction 50%(15% - 50% in 2sec)

Full Strength Excalibur
Comfort Excalibur <<< Recommend
Basic Exalted Blade