User blog comment:B214/Question and Answers 6/@comment-12.188.116.56-20190716202632/@comment-24595619-20190717020157

Elucid could only create a replica of Boosted Gear since Issei descarded body was still inside of the Dimensional Gap, then used Sephiroth Graal to complete it. He can't just create replicas of all of the other Longinus with a suitable source and even with the Boosted Gear replica, he needed the souls of other famous dragons to power it with every use.