In the last 500 years, Jason learned many new techniques that were related to blacksmithing and rune inscribing.
As such, he was able to forge the weapons and armor Jennifer wanted to her fullest satisfaction.
Using rare materials that had a high affinity with Souls, Jason told Jennifer to separate a thread of her soul and insert it into the searing hot metals when he had been forging them.
This was rather difficult for someone, who had never even accessed her soul, to begin with.
Thus, it took her quite a few attempts, and luckily Jason's guidance helped her complete the entire process easily.
While Jason was focused on forging, she had to maintain control over the soul thread, preventing it from being naturally retracted.
Because of that, she began to sweat profusely, while Jason used his own energies in order to redirect Jennifer's soul thread and move it in a better direction.