My standard disclaimer applies…
I’ve been doing solder with easy solder, and I find that to pull it
apart I have to have two pairs of pliers and pull very hard. I’m big,
so that’s a lot of force. Hard solder should hold better.
If your joints are weak, it could be because they have not been
properly cleaned and fluxed, and/or the improper amount of solder. You
could try self-pickling flux, or pickling before you solder to make
sure the silver is clean.
The standard disclaimer: This is from my four weeks of self-taught