If you want to only engage in the legal work of patent disputes, you should only have a lawyer's qualification certificate and a lawyer's practice certificate;
If you want to just write and apply for patent cases, you need to have a patent agent qualification certificate and a patent agent practice certificate.
And if you have time to take the exam, I suggest you take both the lawyer qualification certificate and the patent agent qualification certificate.
Considering your mechanical and electrical integration in 1995, we should be about the same age (I am 37), so it is not recommended that you take the Master of Engineering or the Master of Intellectual Property Law, because both of them are only academic certificates, which will not be the most direct help for your future lawyer practice, while the lawyer qualification certificate and patent agent qualification certificate can help you directly enter the so-called patent lawyer industry, hehe.