'Fixing' energy in the astral is done by understanding the occult nature of the Pentagram, how Spirit manipulates the Elements towards manifestation on the various planes.
A great book on the subject is the Sefer Yetzirah
If I were to do it, I would forge a sword and breastplate, and it would be super expensive haha..
But with the least amount of cost in mind, I would make a scroll as the anchor. Something like this:
Except with a sword and armour and shield and the relevant construct-words.
There is also the concept of the 'breastplate' of the High Priest:
(-source by 'inspect element')