Gryntard's will temporarily reduce the weight of the item it is cast on. Both the reduction in weight, and the duration of the spell depend the caster's skills. At around guild maxed misc and reasonable methods, you can expect the spell to last around half an hour. Repeated casts will increase this, but with highly diminishing returns for each successive spell.

 

The spell is limited to reducing the weight to a quarter of the original. If a single cast is not sufficient to reduce the weight to this limit, the spell can be cast again with further weight reduction. Skill may prevent you from reaching this limit however.