What is meaning of the phrase 'b' juses'?

It is a corruption of "By Jesus," and is a mild epithet used to express disbelief or amazement. I believe " Jesus ! " without the " By " expresses shock, etc. as above, but is not an epithet [ a disparaging name ]. However, the older slang usage, " He beat the livin' B'Jesus out of him " indicated that the " B'Jesus " was used as a strong adjective/pronoun emphasizing the severity [of the beating administered]. I've heard this exact dialogue in several older Hollywood gangster-type movies, names of which escape my memory, at the moment. It's used more usually to express severe action. "I was stoned to the bejesus." "He shook the bejesus out of it."