strengthless (?.)

• anemic
• asthenic
• bloodless
• chicken
• cowardly
• debilitated
• drooping
• droopy
• dull
• effete
• etiolated
• faint
• faintish
• feeble
• flabby
• flaccid
• floppy
• gone
• gutless
• imbecile
• impotent
• languid
• languorous
• limber
• limp
• listless
• lustless
• marrowless
• nerveless
• pithless
• pooped
• powerless
• rubbery
• sapless
• sinewless
• slack
• soft
• spineless
• unhardened
• unnerved
• unstrung
• weak
• weakly