Step 1: The question is about the physical description of the main character in the poem "The Sleeping Porter" by Laxmi Prasad Devkota.
Step 2: The poem describes the porter's difficult life, carrying heavy loads. This might suggest he is strong.
Step 3: However, the poem contrasts his immense inner strength and resilience with his physical appearance. He is described as malnourished and physically worn down by his labor. The word 'frail' accurately captures this image of a body that appears weak and delicate due to hardship, despite the heavy work it performs.