Likely a variant of Rosabel or a Germanic compound
The exact etymology of Rusbel is obscure, often appearing as a rare masculine variant in Spanish-speaking communities. It may be a creative blend or a phonetic evolution of Germanic names containing the elements 'hros' (horse) and 'berht' (bright), though it is sometimes associated with the feminine Rosabel.
Less common today
Rusbel isn't in the latest US Top 1000. It last peaked at #8,512 in 1995.
US births per 5-year period, 1990βpresent (SSA data).