From publisher blurb:
Beware the wise wizard wrapped inelegantly in his esoteric miscellany; he knows many things you do not.
Sneer not at his trinkets and twigs...
The smallest things may be the keys to greater strengths.
The tiniest pieces may turn the tide.
Fetishistic Arcana may be your undoing.
Seek in this tome the secrets of small things, the making of odd objects, the bringing of sundry pieces into a larger whole.
Carry each fetish with care; the wheel never turns for you, lest it turn the wrack in the end.
Fetishistic Arcana is a 25 page supplement of minor magical items called fetishes. Fetishes allow spellcasters to alter or improve the spells they cast. It's written with OSR rulesets in mind and should be easily convertible to the system of your choice.