Pathfinder2e The Spurned hath no fury like alchemy

Thank you. computing.
New map up soon.

1. Record the change in your focus points. you've spent one.
2. New Map.
3. I need to roll will save for the Goblarian. Ex+4, level+5, Wis+0= Will save: +9... 1d20+9
We will use your activation roll result as the Save DC.

The goblin is stunned 1, for 2 rounds. (*Yes. you can attack a stunned target, but I will check the core rule book regarding the stunned condition and spells that cause it).

Tarquin has 2 actions remaining this turn. I shall inform you of an option you currently have. At 5th level the Psion gains Trance. You may enter a Trance state to continue to use the Dissonance psychic attack, for free (no cost in focus points) as long as you continue to successfully activate it, or end the trance. it is an option you have. (*This capacity was created for the psion class as they do not have the ability to use unlimited cantrips as other casters do. it also gives psychic attacks that "Speed of thought" feeling.)

Larkin bringing your holy symbol up as a focus was a part of your casting of Spiritual Weapon, and you directed the ArchMage Staff to strike. According to the spell description you are at the moment out of actions this turn. You may sustain the spell for free in the following round(s), but each time you direct the weapon to strike counts as if you have attacked in melee as well. in the next rounds you may attack with the spiritual weapon 3 times per turn if you should so choose. Just like the speed of an archer firing arrow after arrow...

However, directing the spiritual weapon to strike a different target and/or move will cost one action via the "Sustain a spell" action.

Won't that leave Tarquin vulnerable to attacks by the other goblarians?

Can he target the other goblarians?

1. No. Trance does not cause a penalty to perception, movement, or anything. The limitation is that it must be a repeated activation rolls of the same psychic attack.
2. Yes. You can change targets.

The power of faith, when the divine grants a miracle...
God does not go half way.*

You do not have to waste actions to "Sustain" a miracle with your personal energy; however, every command given to the divine Agent granted to serve you in this moment of need, does count against you. Making the weapon attack counts as though you had attacked, commanding the weapon to change targets or move... that will require the sustain action as you must commune to command.

In essence, you have the psion "Trance" feature as long as you command the spiritual weapon.
(*Though god does say, "It will be in accordance with your faith". i.e. This is why all divine miracles are not "Maximized" and "Empowered". We are the stumbling block, it is our faults that create our limits.)

Such things may have become class feats for other classes. Yet, the weapon trait "Parry" costs an action to gain its benefit of a +1 AC.
normally Staves have the Parry trait...
If I recall correctly, Your Elven Sword of the Sirocco has ALL of the properties of a least staff of the tempest.
Wielding your blade to defend yourself takes one action to manipulate/interact the weapon.

As per the Staff, you wield your weapon to defend yourself. Gaining a +1 to AC. there was no statement requiring this defensive grip to end if you do not keep spending actions on defending your self.