The Moringponia Spear description states
“-Additional critical for Finestra
Critical rate changed to 4% per skill level”
This effect doesn’t show up on the Finestra skills information when the weapon is equipped. Finestras effect stays the same as if a weapon without the skill is equipped.
I’m not sure if it just the information not changing or the effect isn’t working. I’ve done some limited testing but the critical rates are just too random to be sure if it has an effect or not.