Force your own will?
That was not really much to work with, but Eri decided to at least valiantly attempt to do so. He continued moulding and shifting around the bits of djed that formed the shield currently wrapped around his hand, and stopped fiddling with it after he decided that he was not going to make it as smooth as the one he saw Coren made until he had more practice. He made a note to go back at night and practice the shaping process to get better at it. His shield now looked like what a kid would make if given lumps of soft clay and it was honestly not very aesthetic. How it looked was far from important though, for the mage had informed him that the quality of the shield depended on the quality of the shape, and so an ugly looking shield would probably be a poor one.
Eri looked down on his shield again, and resisted the urge to tap into his magical sight again. It would be more accurate for him to work on it in his current state, not to mention less draining on him. He gave the expressed djed a final pat, then he simply stared at it, wondering what he could do to make it, say, block light. How would he go about doing it? He continued staring at it, but the shield around his hand was being stubborn, and ignored his valiant attempts to do so. At least he knew that staring and willing it to block light was not going to make it block light. Eri lightened his gaze on the shield, crinkling his nose thoughtfully as he racked his brains for ideas on how to task his shield.
He thought about the djed extraction process and the shaping process that came after. If he used visual imagery to achieve those two phases, and just like he did with Flux, would it work if he simply used any kind of imagery in this case? It couldn’t hurt, and he was sure that the mage would let him know if he was about to go wrong, though he doubted that there could be anything serious from a shielding accident, if there was even one in the first place. It was simply too defensive and safe an art that he wondered why he had not picked it up earlier. To him, it was like the polar opposite of Reimancy, where the overgiving and accidental self harming rates were mind-numbingly high.
Turning his attention back to the shield, he decided to now treat the gathered djed not as clay, for that part of the process was done for now, but as a messy clump of thread-like objects. He used his other to reach for it, and he realized that with enough concentration he could will the shape of his shield to be like so. He wondered if it was his perspective of it that changed, or the actual astral manifestation. Regardless, it served his purpose and he clumsily began weaving the threads of djed together. What he consciously wanted to do, he did not know, but in his unconscious mind he knew he wanted it to block light. Thus, the Vantha worked according to instinct, knitting a clump here, weaving more strands there. He single-mindedly worked towards a purpose, though he was not consciously thinking of what he wanted to achieve. He simply proceeded with one step, then somehow seeing some sort of imagined pattern he went for another step, followed by another. It was really like the process of scribbling one’s imagination on paper, and he wondered if there was an end to what he was doing.