cloak chant= agility or armor? and shield

What should I chant my cloak? With agility, I would gain dodge, armor (to a lesser degree) and threat. With armor, I gain threat (thanks to armored to the bone, but to a lesser degree than agility) and armor. With defense rating, I gain dodge, parry, shield block, and armor (dodge and armor to a lesser degree than the formers). I'm leaning to agility, but I'm not really sure.

As for my shield, I got titanium spikes since I'm defense capped, but I'm wondering whether I should put the defense rating back for the miligations

I think most people would say go with armor to cloak.

Put +18 stamina on your shield. NO wait, put defense. No, no no, put stam.
(There's more than one thread with people going back and forth on that).

Put stam or defense on your shield; the spike is not a decent alternative.

If you need to gem or chant for defense because your not over the floor; the shield is one of the bests places to do so. It's better to enchant the shield as you sacrifice far less to put defense there then say if you used a defense gem.

IE: to enchant your shield you lose 18 possible stam, but if you use a socket you lose possible 30 stam; yet both give 20 defense. Same is true for your breastplate; 22 defense for 275 possible hp (like 25 stam). Therefore if you need the defense, your shield, then your chest plate are among the better places to get it. The cloak slot used to be a great place to eek out some defense, as previously it was one of the best enchants for defense vs EH trade offs; however with our stamina so high these days the armor is far more valuable then it once was.

I'd stick with armor on the cloak, and stay away from defense enchants unless your still struggling to reach 540. I personally use titanium plating on my shield... but that's cause I had some extras kickin around and the stamina enchant is really not that great @ only 18 stamina. If both enchants were free, I would have gone with stamina.

Following onto this question, currently I'm well over the defense cap, sitting at 40.6k health unbuffed, hit capped, 34 exp and wondering if my shield enchant slot could be better spent than the +20 def I have sitting on it right now. Anyone have a math breakdown for the three contenders, +20 def, +18 stam, or +81 block value (titanium plating)? Thanks.

Apologies if this discussion has happened somewhere already, I couldn't find it in searches...

It's simple, no need for any math tbh.
If you need defense or avoidance - go +20def.
EH? 18 stam
Titanium plating is probably a weak choice for any type of fights (well, maybe for heroic Anub's adds if you're already unhittable; but I think I'd use next choice then)
For threat and 5mans shield spike is better thing, as afair it ignores the armor.