Well lets see: "Skin of Stone" adds with DNA 1332 defense, "Survival Instinct" adds another: 918 with DNA so that`s a total off: +2250 Defense
(Skin of Stone adds only Short Range Def. no additional long range defense)
Both will cost you 20 Skill Points + 20 DNA Points.
You have a much better Buff that will cost only 10 Skill Points + 10 DNA AND includes the whole Party, thats Important for Bosses with AoE Attacks.
Yourself buffing : 2494 Def.
But your not alone on a Raid:
Radiant giving +1260 Def.
Mystic Totem +1656 Def.
Druid: + 1262 Def.
to name not all.
So even if your Gear is "only" around +15 you should have reached at least 4K Defense on your own without any other Buff coming from the Party. (speaking of Carus Gear here)
Including Buffs from the Party you will come close to Defense Cap pretty Easy.
here is a link, that might help understand the Defense Formula:
Short Saying your doing ok with 5K Defense already, thats like 80 % reduction:
So Defense is the least Problem a Protector have to worry about.
Equipment well, depends on the Gear you choose.
Enchanting the Armor with Block Success 0.40 % Xeons
-Conquerer (adds Fire resist)
-Sacred Pattern (adds Light resist)
-Twilight (adds Elec resist)
depending on the Armor Bonus
so you will need a addition like:
Try to reach as much % Block Success you can get with help from a Cell:
those should add Block and Magic Damage.
(well the Block Bonus with a Physical Cell is higher i think)
So working on a Protector is not easy. But surly can it be rewarding.