Jim Gormley, whose 19-year-old son was stabbed to death in Blantyre last year, said an announcement that the maximum sentence for carrying a knife is to increase by one year to five years will do little to deter habitual criminals.
He also hit out at an announcement by Justice Secretary Kenny MacAskill that amendments will be made to existing legislation making it clearer to sheriffs and judges they have the power to impose a consecutive sentence on offenders who commit crimes after being released early from prison.
The changes, which will clarify the powers available to the judiciary, are aimed at ensuring more offenders complete their original sentence before starting a new one, rather than serving them concurrently.
Mr Gormley said it "beggared belief" that the legislation to do this is already in place but is not fully understood or being fully implemented.
He said: "To me, MacAskill is just paying lip service here. If they were really serious about tackling knife crime then they would introduce measures to really make people think before they carry a knife. For habitual criminals and people like Daryn Maxwell, who murdered my son, they'll not be put off by another year. It really makes no difference to them.
"And this is only a maximum sentence – how many people are actually given the maximum sentence?"
Mr Gormley added: "As for clarifying legislation on concurrent sentences, it begs the questions why is it not clear, and exactly how up to speed are our judges if they don't know it's available to them and how to use it?
"To me, concurrent sentencing should be completely scrapped. Why should someone be able to commit two crimes and only serve one sentence?
"We met with Mr MacAskill and the areas we wanted him to look at were the length of different terms in jail, concurrent sentences and bail. We wanted action on bail and accused people being released on bail despite having numerous previous convictions or outstanding cases, but as far as I'm aware nothing has been done on this."
A Government spokesman said existing legislation on concurrent sentences was old and in need of updating, something the Government was already looking at.
The maximum sentence for carrying a knife in city centre areas increased from one year to four in April this year in response to calls from the Gormleys and other campaigners.
Mr MacAskill announced the latest increase to five years at a Violence Reduction Unit event in Glasgow yesterday.