User blog comment:B214/Question and Answers/@comment-24098614-20131125092654/@comment-16281343-20131128095837

@anon, The number of pieces needed to use and the type is not a reflection of the servant's potential. Take Kiba for example. He only needed 1 Knight piece to be reincarnated, but look at him now. What is taken into consideration when determining the number of pieces needed to use to reincarnate a being is his/her/its "power" at the time of reincarnation.

Maybe, you are saying that because of Ise that consumed 8 pieces even though he is practically worthless in the beginning. But take note of Aza's opinion that Ddraig consumed most of the 8 pieces (its like 7.9 Ddraig, 0.1 Ise... not sure of the number)