Recommended oil for this Accord is 5w30.
You urgently need to change the oil company and the viscosity.
I'll suggest as follows
Choose the engine oil having 5w-30 Viscosity.
Total company blends the oil for Honda. So I'll suggest to choose Total Quartz 9000. This oil has 5w-30 and this is best oil. But flip the bottle and read by yourself. It must be imported from Singapore. Your car is expensive, so don't use cheaper oils.
Shift to this oil and drive few km with light foot. Am sure that blue smoke will disappear forever. You can check it by pushing accelerating paddle upto 5~7K rpms in neutral to confirm it.
I know, the blue smoke indicates that rings have gone weaker and engine has started burning the engine oil. But never go for the 20w-50 oil which mechanic has asked to use. And also the previous owner was using less-compatible oil and from less known company.
I can be 90% assume that your engine rings are perfectly OK. Only you have to change the company & viscosity.
I have example of my own car too. But will furnish later if necessary.