Michael Mensah, 18, was arrested in September last year, and police found a five-inch blade in his trainer and a samurai sword in his car.
Mr Mensah, of Greenford, denies murdering Mr Mayley, 24, who had learning difficulties and was stabbed in the heart on Ruislip Road in Greenford on February 7.
Ryan Beresford, 19, of Acton, and two 17-year-old boys, have also denied murder.
Mr Beresford, Mr Mensah and one of the 17-year-olds deny attempted robbery.
The other 17-year-old has admitted one charge of attempted robbery, the court heard.
The teenagers cannot be named for legal reasons.