One of the things holding Core Guardian back in PvE is that Dragonhunter gets at least 30% damage in modifiers from their traitline (Zealot's Aggression, Pure of Sight and Big Game Hunter), while for Core, Unscathed Commander only grants 20% when you have Aegis active. One single hit from an enemy reduces a Core Guard's damage by 20%.
On a golem this is fine, but in actual gameplay, not so much.
Many have suggested changing the trait to give you 20% damage while retaliation is up, which is a lot easier to manage. Problem with doing that though, is then DH will just run the Virtues traitline and be even more of a DPS beast.
So I suggest moving the passive 20% damage modifier from Unscathed Commander and tack it on to Inspired Virtue, which means only someone running with Virtue of Justice / Resolve / Courage will receive that modifier, which will not apply to DH because when the Dragonhunter trait line is equipped, Virtue of Justice becomes Spear of Justice, etc. Same goes for Firebrand as their F1-F3 are replaced by Tome of Justice et al.
Then replace Unscathed Commander with some other Adept trait.