Thanks! :D
In my free time when I couldn't code I jotted down a lot of different ideas for abilities/items to make sure that there were interesting enough decisions for the player! I normally hate when items/relics are just number boosters, so I tried to come up with interesting interactions between different items/abilities as well, but that does lead to a bit of confusion sometimes. :P
For stats that have an expression in the form of X (stats and percentages), that means that that value is based on your own personal stats! So Prickly Shield inflicts bleed on the enemy equal to your DEF stat. And this updates throughout the game if your DEF is ever changed by temporary or permanent effects, but it definitely seems confusing before you get any DEF.
For the Greatsword (I'm assuming), it activates whenever the player has an attack that does more than 10 damage, and it causes the attack to deal an additional 3 damage (which scales with your ATK as well). It doesn't mean the Greatsword itself has to get to 10 damage with its bonus, but that the player just has to have a 10+ damage attack through any means. I could definitely explain it better though! ^^