Every second patient I inherited is like this. Here's what I do, which works better than anything else I've tried:
Lay out your plan to switch him to a long acting benzodiazepine which you will then taper slowly. Tell him it is not safe to stay on Xanax, given his complaints of falls, memory problems, and dizziness. Anyone who asks you why you are tapering him gets the answer "because it is not safe or effective for his illness and not FDA approved for his diagnoses." Tell admin he is a fall risk, which he is. After you taper him off the benzos, start working on reducing other polypharmacy.
Do not engage in bargaining with him anymore. Be pleasant at all times. Never go over time. Keep your visits with him short and to the point. Listen to him actively for a few minutes only. Then do the focused exam. Kindly offer to refer him to a different psychiatrist, since he is unhappy with your plan. The less you try to "fix" him the less he will try to manipulate you, and the better he will likely get. The last psychiatrist or four couldn't fix him either, hence the nonsensical med regimen he already has. He will only get better with therapy and taking personal responsibility for his recovery. He will never do that if you keep trying to rescue him.
If he threatens you, tell who you need to tell he threatened you and say that you will never see him again, and refer him to another psychiatrist. Document everything, especially regarding suicide risk factors, protective factors, and prognosis. If the prognosis is poor, document why.