I agree, a rare but not unprecedented combination of a Latin prototheme (i.e. taken from prosaic Latin speech, not used a prototheme in Latin names which are unusual in not retaining the Indo-European name traditions found everywhere else from Spain to
India) and a Germanic deuterotheme. /s/ for Latin /ks/ is unusual but is recorded in some Italian dialects. The dominant sense of
Felix is fortunate, happy, a popular category of Indo-European name themes; berto/berta are the declined forms of -bert, "bright", the inference is "glory". While it's tempting to construct a combined meaning these would be selected as potential themes independently, and the combinations then chosen for a variety of reasons that may result in contradictory themes being combined (e.g. "dark bright", "battle peace").