Stats in the anime/novel explanation

I need some help figuring out how the hell this damn power system works. I swear to every god out there, that this series' DAMN status menu and stats make NO SENSE! I can't find ANY idea of how it works! Not only that! But apparently, some power up methods are cannon, while other, are not!, this, is how I think it works:

[Name: Naofumi Iwatani]

[Race: Reincarnated Human]

[Job: Shield Hero]

[Age: 20]

Stats

Level: 50

[HP]: 10,000

[SP]: 6540

[MP]: 6530

[EP]: 9700

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[ATK]: 077

[MAG]: 653

[DEF]: 995

[AGI]: 544

[DEX]: 567

Equipment

[Barbarian Chief Armour] +235 [DEF] +50 [AGI] +50 [DEX] Defence Up-[Medium] Impact Resistance-[low] Slash Resistance-[Medium] Earth Resistance-[Large] Fire Resistance-[Low] HP Recovery-[Very Low] MP Recovery-[Low] Magic Power Up-[Low]

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[Paladin's Shield]+5 (Awakened-A) [SR]: +330 [DEF] +90 [MAG] +75 [AGI] +85 [DEX] +265 to [Light-RES]-[Equip Bonus]: Light Shield, Blockade

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[Item Enhancement]-(Level 15): +15 [AGI]

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[Weapon Enchantment]-(Level 30): 25% less damage from [Light], [Dark] and [Holy] attacks

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[Status Enchantment]-(Level 20): +50 to [Light-RES]

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[Weapon Mastery]: 72/100

or something to this effect. But apparently, Itsuki's rareity power up method is cannon, but motoyasu' familiarity bonus one isnt?! Please, help me understand. Hell, help me fix it so it's overall just more cooherant!