It's actually more of a liability in the final hunts because of its slow rate of attack and low combo rate. The Masamune becomes much more important because of its astronomical combo rate.
Also, it's not the only method of getting the spear - there is another 1/1000 chest that will contian the spear. Sometimes.
I think the fact that you have to go through that weird rigamarole shows that you weren't really supposed to get the spear. I'm okay with that - it's an easter egg, and it's absurdly powerful to the point that it doesn't fit well into the storyline.
Wait, we're in agreement that you aren't supposed to get the spear.
In that case, I see nothing wrong with sticking in something that 99% of playes will never see.







