I've used soft solder to repair glasses frames. More than strong enough
& avoids the heat needed for silver. I suppose it's possible to control
the heat needed for silver solder, without destroying the frames, but I
can't & it sounds like you wouldn't be able to either (said without
aspersions).

'Though I have repaired frames, nowadays I don't bother, as a new pair
is $12 (shipped) from Zenni (http://www.zennioptical.com/). I'm a very
satisfied customer, as are others here.

Bob