does a weaker speaker mag mean less tone? does a bigger one mean more? i have no clue how the mags affect the speaker.
I think the stronger ones require less magnet for the speaker to work correctly because I have noticed that neodyium magnets on speakers make for an incredibly light speaker.

I have no idea though, just a guess. I'm saving a facepalm for myself when I find out the correct answer.
I think lower power handling requires less powerful magnets. The actual size and strength of the magnet has less to do with the way it sounds than the type of magnet used. Alnico magnets were used in most vintage guitar speakers, which is why most vintage style speakers have lower power handling. Ceramic was first used as a cheaper alternative, but led to the possibility of higher wattage speakers. Neodymium is becoming popular because it's a much stronger magnet for it's size, so you can get high power handling without excess weight.
The magnet weight doesnt always determine the speakers tone. Alnico speakers the magnet is usually heavier as it is weaker than ceramic. Some alnico speakers can have 30oz weights others much less. The speaker size, cone material etc goes into the equation. "7oz alnico magnet in a british speaker" is not a whole lot of info.