So, I started playing with G5, and it had Sorceress and Shock Trooper. Those two classes are everything I've wanted Guardians and Agents to be. As it stands, Agents are sub-par because of Action Economy; if you invest in spells, you never want to invest into any weapon skills except Parry/Evasion. Same is true for Guardians, heavy investment into melee/missile damage just gets outclasssed by creation damage, and you can do only one, which will never be creations because more skill point costs.
Both shares a common problem: Weapon attacks are dependant on two stats instead of 1 like Intelligence/Essency Mastery (in G5, it was even worse, Intelligence also gave Essence). They are also dependant on two skills, and they aren't even that cheap to raise. QA is worse than spellcraft, and Parry/Evasion, the only decent-ish skill, needs heavy investment (+ Endurance investment) to be good. Skipping melee is painful because rare thorns are rare; and skipping ranged makes certain fights harder, reducing your total tactical options, especially as you don't have a Thahd like leap (I really recommend adding one to Weapon Shaping).
I propose merging the two weapon skills into one: Weaponmastery (+8% to weapon damage), two physical skills into one: Physique (+10 Carry Weight, +5% Weapon Damage, +1 Initiative), no Evasion from this because I think it'd be too much. This frees up a slot dedicated to the new weapon shaping skills. I suggest it be focused on quick self-buffs and buffed weapon attacks. The damage from the weapon attacks would scale from Weaponmastery + Physique, and the bonus damage from the Weapon Spell would be increased by this skill (+25% Damage becoming +100% at high levels of Weapon Shaping); getting the triple-skill boost damage spells already get (Intelligence + Spellcraft + Battle Magic).
While Agents might still be subpar, if the self-buffs present in this tree is unique and strong enough compared to Blessing Magic (like Lifedrain, Battle Frenzy, for example), it will be a worthwhile investment, and Parry/Evasion is decent on Agents too; letting them have a unique niche compared to Sorceress. Same for Guardians, they will be super-warriors since they wouldn't need blessing magic at all; even Mental Magic if Guardians' Roar remains on the Weapon Shaping tree; and spend their extra essence to shape. Guardians are already better than any of the previous games; I just am sad Agents can't really use the Weapon Shaping because it gets outclassed by Blessing Magic when boosted by Spellcraft and high INT.