Mr Purser said the 23-year-old felt very lucky that Mr Mitchell had not been carrying a weapon of any sort.
Meanwhile, a fan who ran onto the pitch at the Emirates Stadium during Sunday's match between Arsenal and Manchester United and pushed United defender Chris Smalling has been charged with common assault.
His solicitor told the court: "He can not explain what came over him yesterday morning". "It's been racist abuse, it's been anti-semitism and now it's real fear for the safety of players".
"The Club will also support any further punishment this individual may face in the eyes of the law".
"Drastic action is needed - either through points deductions or by emptying stadiums and making clubs play behind closed doors".
"Every case will be looked at on its merits".
"Football has a responsibility to take action".
"In that situation, you'd need to speak to the match commander and they would have to be together and establish how the safety of the players is of paramount importance".
Why are EPL teams making such a big statement in the UEFA Champions League this season
"We now have a man in custody for questioning and will be working with Birmingham City Football Club as we fully investigate what happened".
The spectator, clad in a Birmingham City jacket, attacked Grealish from behind, his blow landing on the side of Grealish's head. "There has to be the right message here", he added.
Birmingham City has confirmed the supporter has been given a lifetime ban. "I've captained Aston Villa and I've scored the victor". It was unbelievable, in front of our fans and after what happened in the first half.
"We have had three incidents this weekend, we have had other incidents this season".
"Following the incident on the pitch involving an attack on an Aston Villa player; a man has been arrested and [is] en route to a custody block", West Midlands Police said on Twitter. "Unfortunately some mindless moron has gone on the pitch, attacked Jack and you have 15,000 idiots clapping him".
"I was just unaware at the time", Grealish told Sky Sports when asked about the attack.
Paul Mitchell's lawyer told the court family members had been forced to move out of the Birmingham area after the "high-profile" incident because of on-line threats.
Enquiries are ongoing relating to objects being thrown at officers, while offensive social media posts directed towards Grealish will be reviewed.