Came up with all of these at 12 in the morning (my sleep schedule is a wreck). Some of these may not be balanced but these are just concepts so I don’t really care. You can do your own interpretations in the comments.

Items:

Greed - each shopkeepers/beggars bombed will either drop more helpful rewards or be detrimental

Lust - Contact damage immunity + contact with enemies will charm them. Each charmed enemy gives a damage buff. Base damage will degrade for the room once the charming effect wears off

Pride - Gives all stat multipliers (except shotspeed and luck. Instead gives +3 luck) on pickup. Stats degrade by 25% with each hit taken. Base stats can be degraded 3 times after the boosts are gone.

Wrath - Completing rooms in quicker time will grant extra rewards. Guarantees no reward if you take too long. Random stat up (except shotspeed) if you beat a stage quick enough, random stat down (except shotspeed) if you take too long to beat a stage. Gives bonus item from beating Boss Rush and Hush.

Envy - Double items, but all item qualities are 2 or below.

Gluttony - Small stat up for each full red heart container you have. Full bone heart containers give a smaller stat boost. Small stat down for each empty red heart container/bone heart container. For each soul/black heart in your health bar, a small speed down. Picking up eternal hearts grant damage up for the current floor.

Sloth - All stats down when encountering items with a quality below 3. Finding a quality 3 or higher will give a stats boost.

Transformations:

Sinner - Obtained by collecting 3 sin items. 1.2x damage multiplier, but double damage is taken by the player.