The JV card sounded incredible, and it really was. The reason why it was not used so often, however, was that the greater the augmentation became, the more aether the card would burn. Although the top limit was capped, and adding more JV users would merely increase how quickly that cap was reached, the rate of aether consumption made it so that the card was not viable for long term use.
Even now, the only reason Nero and Vilhelm were using it was because they were Initiates trapped inside a battlefield filled with Arcanists. Arcanists were naturally physically stronger and faster than Initiates, but the difference was not so massive, which meant that using the JV card allowed them to not just face, but even retaliate against their opponents.
