Upgrade item level requirement

[StrawHat]

So, I'm not entirely sure how the mechanic works. This is not an issue for me anymore, because I have already went past this point, but it's something still needs to be noted. I was unable to feed some type of lower tier weapons to my profane weapon in this stage, as well as in the previous stage, whilst still falling under level 45 requirement. The image provides a better explanation. 

 

 

[Zimb]

This makes sense...