2 W if it is actually a 1 W amp; assuming some design margin it could put out 3 or 4 W, oh my.
Who's argument? jim19611961 made the point that an amp with considerably less power rating could still destroy a tweeter (or by extrapolation any driver), and you countered with "Then, if we go to an extreme example, using a 1 watt amp, that is not a guaranty that it cannot blow a tweeter?" If I followed your statement, then a 1 W amp is not a guarantee if the driver is only rated 0.5 W, if we want extreme examples. I suppose we could throw about all sorts of counter examples to prove whatever we want, but I'm not seeing the point... I guess I'm confused.
"After silence, that which best expresses the inexpressible, is music" - Aldous Huxley