Strong-meaning names run across origins because the theme is universal. Hebrew tends to carry the meaning directly (Ezekiel, Gabriel). Greek favours warrior roots (Alexander, Andreas). Celtic languages often approach strength poetically, through images of stones, oaks or stags.
Direct versus implied strength
A direct meaning like 'brave' or 'warrior' does the work for you. An implied one (rock, oak, lion) gives the name texture. Both are valid. If you want a strong name that does not wear it too heavily, lean toward the implied picks.