The story you may have heardWiktionary's Portuguese entry derives baraça from Arabic marasa 'rope', and further from Syriac maršā and Akkadian markasu, which made 'embarrass' look Semitic. Standard references (Corominas, DECat) call baraça of unknown, probably pre-Roman, origin; the Arabic route needs an unexplained m- to b- change and lacks the al- article that early Arabic loans usually carry.