Psionics, Magical Talismans, and spirit vessels


#1

I have made talismans and my experience up to now tells me a few things

  1. having a spirit involved makes it more effective than simply consecrating it with nameless energy

  2. daily invocation of the spirit over the talisman seemed to maintain its effectiveness for a period (30 days / one lunar cycle)

  3. beyond a certain period the talisman seemed to lose effect.

Bigger spirits would seem to be necessary for bigger tasks.
But if I wanted to have a talisman for an intermediate strength task,
I think trapping a spirit and enslaving it within the vessel might be the way to go.
However, this type of spirit is going to be less powerful.
What class or type of spirit is this going to be?

Thanks in advance for any comments from those who have worked with this