One of the main aspects of Hero and all of the future Scion classes is that while they share weapon types with other classes they use them completely differently. Hero Sword or Hero Talis are basically completely new weapons gameplay-wise while reusing existing weapon assets. So don't expect to be using your Hero Talis to be casting techs, they have actual PAs with it instead.
While Hero can cast techs, the only techs you'll really be casting are support techs mainly for yourself (such as Megiverse for healing or quick casting Shifta and Deband to keep the Techter's buffs up on yourself.)
It should also be noted that future Scion classes coming in EP6 CAN be used as a subclass for the older classes, but all of them cannot have a subclass when set as your main class. So when Phantom comes out on EP6 launch you could do something like HU/PH and actually enjoy having high damage modifiers similar to Fighter sub while being able to cast techs too (again mainly support techs tho, there really isnt any viable melee + teching builds outside of wand bonking).