I lived in Israel, also met some "guys" who did some "stuff". I've never seen or heard of any Israeli ever using a .25 for anything. May have happened, but it sure ain't standard. Don't know where that info came from.
For starters, the Mossad has no "standard issue" anything, tools are used from where and when you can get them. The source of the ".22 as issue" myth is actually interesting. I got this info from the old El Al security guys I did my first pistol training with. El Al, Israel's national airline, has had skymarshalls since the mid-1960s. To avoid shooting through airplane skins, not to mention those of other passengers, they used Beretta Mod.70 .22 pistols. These same pistols were now available in any city where El Al had an office. If someone needed a pistol for something, that now became the easiest source. I'm sure it was not a common practice, as then anytime someone got shot in the head with a .22 the police would think they were all done by the same people, not something an intelligence organization really wants.
BTW, those El Al guys were blazingly fast using Hi-Powers and the "Israeli Method". And there are a few one-handed techniques that the method includes.