Ranking all relics since im bored:
Frog Totem: A
Pretty good relic, but it's not conductive fore some reason. More efficient mana per turn than wizard's cap; 3m+2m from spellbook/4m from cap.
Windmill: A
Again, more effective than crimson energy, which needs 3 spaces when placed in a corner and windmill only two.
Tusk: B
Worse than glass bottle most of the time.
Stopwatch: A
Belt of knives is better for cleavers, but stopwatch is better for anything else really.
Spicy Ginger: B
Consumables are quite common, but outclassed by belt of knives which adds 3 damage if you have a shiv or a hatchet.
Spice: B
Pretty good relic for water flasks or old log. Synergies with seasonings.
Shield Spirit: S
Allows you to use assassin's dagger or cleavers with only one energy, Synergies with hercule's pavise.
Sandwich: B
Triples the effect of seasonings.
Ore: D
Outclassed by almost every relic, even the niche ones like spicy ginger because consumables are easier to find than gems and it's diagonal as well.
Mouse Wood: S
Makes arrows one shot everything.
Hourglass: C
Very niche. Pairs well with beserker's club or one of the ethereal weapons.
Glass Bottle: A
Free extra damage! Makes shield spirit or soldier's buckler useless.
Fluffy Cotton: A
Wands provide an easy way to refill one mana per turn. The mana bonus originates from the fluffy cotton, not the wand.
Coral: A
Scales more with extra energy.
Conductor: B
Good with doru/pick axe.
Cleansing Flame: S
A must-have for cleavers.
Bombstone: C
Its only use is for ethereal weapons. Good with etheral blade and makes it deal 72 damage per energy. It appear i underestimated it for arrows, so now it's a c.
Barbell: A
Similar to mouse wood but with a weaker effect.
Belt of knives: S
Makes shivs or hatchets give +3 damage to adjacent weapons.