They say there was only 48 Teigu/Imperial Arms. But I only counted 36. So they should probably have 12 more.
The fact that they only know about a few of them leaves room for imagination to create random items to fill the void left by the ones we never see.
Maybe there are some missing Imperial Arms/Teigus that that have never been used or discovered before. Like a one that can travel through time, a one that can grant you any wish, a one can resurrect the dead or more.
Unfortunately, they're not sure if the 12 other Teigu/Imperial Arms are destroyed or remain lost or not.
What do you think?