to make it seem like it's still a holy artifact to the commoners/citizens because it will be a problem if it got revealed that the "holy grail" was not holy anymore and can cause the people to panic and there might be a civil war if they know the new power of the "holy grail"
+ and as they revealed in a chapter that it was used to revive a dead person, this can turn into a really worse case scenario. People fighting for the "holy grail" because of some rumor that it can revive a dead person and maybe it can do a lot of things.
this are just my opinion ╮(￣▽￣)╭
Good point (づ￣ ³￣)づ
Why do they still call it "Holy Grail" when it is not so holy anymore? Like tf?