This word is acceptable for play in the UK dictionary that is being used in the following games:

• Lexulous
• Wordscraper
• Wordosaur

adj. causing weakness.

That has a tendency to debilitate; that causes or tends to cause debilitation.

adj. causing debilitation

"MP's publisher, Eileen Tabios, will handwrite all texts into the Tiny Books' pages and books will be released to meet demand for as long as MP is able to source tiny books -- or until the publisher gets arthritis or debilitative carpal tunnel syndrome."

debilitating   

enervating    enfeebling    weakening