to demen, i knew that one as well but i was saving it for later in my magick combat section and for hex, i learned allot of things from allot of ppl books etc. I can't remember every source but what i can say is spiritual books are your friend and when using the chakras knowledge comes from all kinds of places
i also learned these shields via duels, i did a practice duel years ago when i learned about the illusion shield, i learned about its amazing effects to fool you can cause you to misdirect energy which in results cause spells to be aimed at nothing or something against you. You can even make these shields even more intricate be create
I created a shield a LONG time ago (about 6-7 yrs ago) w/out even knowing anything about them, to be honest, I've never researched about shields.
My shield is a gold/white sphere, it's lightweight, it's comfortable, it cools me down, it warms me up, it does anything and everything that my body needs when needed.
But most importantly IT PROTECTS ME!
My Protection Sphere surrounds me completelly, it stretches out as I do, it doesn't sofocate me & it doesn't get in the way of what I do.
When I need to eat, drink, wear something...etc.
As the "things" come through my sphere it cleanses them so that they enter safe to come in contact w/ me.
Also when I feel fear or have doubts that I may need to cleanse my Protective Sphere what I do is I visualize my sphere already surrounding me but another little ball being created from "My Heart" of the same structure as my sphere. My Heart Ball grows bigget and bigger untill it pushes any negativity, darkness, fear... etc. that may have been lurking around. (This is just mental as I've created my sphere w/ the intent that NOTHING can penetrate it. But even a mental doubt is dangerous).
If I feel that there'a too much darkess lurking around I use my Heart Ball, it absorves all the darkness and it magically disolves it to nothing. Now I have a clean and cleansed space, mind, heart...etc.
At night when I'm laying in bed I make my Protective Sphere stretch as big as the entire house so that every one in it is protected as well.
I also create a Protective Sphere for all the people that I can remember (starting w/ my baby and the rest of my family, friends...etc) making it out of their own Heart Ball and growing until it becomes their own Protective Sphere, then I activate it w/ a small prayer of protection.
It has helped me inmensly to calm myself down when I feel fear or any type of doubt.
I tried shielding my house, car and once even the plane I boarded on, the place where I only sat on of course, lol. It's important to 'shell' your shield as well.
When shielding myself I find that using sound effects is pretty useful.
i have a spell for that in my list using sounds, its called sonic shield. i covered that one too under elements since sound is also and element known as ether, although ether is also the space in which the other elements live. Nice of you to mention you know this, i have not had any other casters mention that one.