The 'minimum' value defined in an attribute's YML is not respected with spells that remove attributes.
Attribute YML:

deity_favour:
  min: 1
  default: 1
  max: 6000

A spell used 'ModifyVariable' to remove some points from the attribute. If doing "/mage attribute deity_favour" it reflects "1" as that is the minimum value allowed, but doing "/mage describe" shows the value has actually dipped into the negatives. Using a spell that adds points to the attribute will add it to the negatives, and the "/mage attribute deity_favour" value stays at 1 until the true value reflected in "/mage describe" surpasses 1.

Also happens with 'Max' values