I honestly do not recommend to buy these unless like me you are getting them purely to encourage the franchise and for "collection" sake, since I already 100% this game and its DLCs back when they came out. As you'll see they barely change anything at the end of the day except for the reload one that is kinda "ok" if you obtained both stabilizers during your playthrough. Otherwise they are not worth the valuable space they take at all.

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NON-DLC Passive Items (For comparison)

Assault Coin - 15% Increased Damage (During Madhouse mode only)
Iron Defense Coin - 15% Decreased Health Loss (During Madhouse mode only)
Walking Shoes - 30% Increased Walking/Crouched Speed
Essense/Secrets of Defense - Each adds a flat 12.5% Damage Resistance to Blocking (Normally 75%)

With both Defense Unlockable Items, no damage is taken from any guarded attack. (75% + 12.5% + 12.5% = 100%)

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THIS DLC Passive Coins

Attack Coin - 6% Increased Damage
Defense Coin - 6% Decreased Health Loss
Instinct Coin - 6% Increased 'Instinct Damage'
Reload Coin - 6% Increased Reload Speed
Universal Coin - 2% Increased 'Instinct Damage', 2% Increased Damage, 2% Decreased Health Loss

Multiple coins are additive, e.g. having 1 Defense Coin, 1 Iron Defense Coin, and 1 Universal Coin will decrease damage taken by 23%. (6% + 2% + 15% = 23%)

With both Stabilizers and the Reload Coin, Reloads are 48.4% faster. (1.4 x 1.06 = 1.484)

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Here's the link to the source of the info. I'm posting this as a review for the reasons mentioned above and because also that info was way too hard to find for what it is so I wanna save some time and money for other people.

https://gamefaqs.gamespot.com/boards/191629-resident-evil-7-biohazard/76931349