The city’s Metropolitan Police service said the 47-year-old was in possession of a knuckleduster and a “bottle containing a substance” when he was detained in Shoreditch on Sunday night.
Officers discovered a crossbow, knives and other weapons when they searched his home, which were sent for forensic analysis.
Police launched a manhunt after a 44-year-old woman was struck in the head with a crossbow bolt as she crossed a road in Shoreditch on March 4.
Ten days later, a 20-year-old man was hit in the neck by a crossbow bolt just 60 metres from the scene of the first attack.
The suspect remains in custody and both of the victims in the two incidents are being kept informed.
Police say they are are keeping an open mind about the motive for the attacks and inquiries continue.
Some Shoreditch residents had criticised the response by police and other authorities to the attacks, according to local media.
People living near the scene of the attacks told how they were forced to live in fear. Many said they avoided windows and rushed to cross streets.
The husband of the first victim was so concerned he placed a written message on a street wall close to the shooting scene warning people to be vigilant.
He described how the crossbow bolt became lodged in her head as she was walking.
But police on Monday defended their response and said they received valuable public support.
“The arrest last night was a significant development in our investigation, but this remains a complex and ongoing policing operation,” said Detective Chief Superintendent James Conway.
“I can also confirm that our inquiries led to the seizure of another crossbow weapon in the period between the two attacks, which is now being dealt with as part of a separate investigation.”
