Worst case scenario: S&W does not fix or replace your gun. At least you weren't injured during the failure. God bless.
I understand that you are 74yo and identify as handicapped and don't want the weight of a heavy steel revolver. If you need something small and conceilable I suggest getting a stainless J frame like the 640. It is stronger and while its a little heavier, that extra weight really helps mitigate the recoil (ouch factor). If your condition affects your hand strength then I don't think a light-weight gun is really helping you: it only increases the felt recoil.
I personally like my very light weight M&P 340 because I forget it's in my pocket.... it's that light compared to my steel guns. But BOY does it sting my arthritic knuckles at the range. I had to try many types of grips to find what works for me. J frames are concealment first, comfort second.
Overall, I like scandium framed guns for their light weight. I own two Scandi J's and one Scandi L frame. But aside from some arthritis, I still have decent health.
ALSO overall, I think titanium cylinders suck. You need to be careful about ammo selection, they're prone to difficult ejection issues, and they're more trouble to clean. I replaced the Ti cylinder on my 386PD (.357 scandium L frame) with a SS cylinder and it's a MUCH better gun, in all regards.
Sorry to get off track....
*I recommend any modern steel J frame for you. .38 or .38+P will stop the bad guy without hurting your hand/wrist too bad.
If you need a light weight revolver my wife has a .22LR J frame (43c) and I'd piss my pants and run the other way if she shot at me! Similar light weight to your PD but very low recoil.