The laws governing weapons here are very simple. Only the law and order/securtiy services carry them. Period. Full stop.
The authorities will take a very dim view of things if they find daggers in your car.
You can carry a baseball bat if you like since that's classfied as sports equipment. Try to have a glove and ball too to keep up the charade. If by any chance you do use it then said authorities will take a very dim view of you too. And your next view after the holding cells and your embassy bailing you out could well be of Doha from the air at the end of the deportation process.