Weighted blanket

Carry on baggage
Yes (<350ml)
Checked baggage
Yes

Certain powder and granular materials inside weighted blankets (e.g., glass beads, poly-pellets, sand, or pebbles) are limited to a quantity of 350 mL or less (roughly the size of a soda can). There are no exceptions for medical reasons. 
Note that if the weighted blanket contains over 350mL of such powder or granular materials, it is not permitted in the carry-on baggage.

Attention

Certain powders and granular materials may require additional screening, and in some cases, the items may not be permitted. We recommend that permitted powders and granular materials that are not required during your flight be placed in checked baggage.

Exemptions on baby food or formula, life-sustaining medication, and sacred or spiritual items may apply.