how would people make the light and heavy weapon properties actually interesting? to me they only seem to exist to facilitate the TWF style, the GWM feat and preventing small species from using the better STR weapons?
heavy i'd probably just convert to a STR requirement like what heavy armours have, i realise it's meant to be more of a restriction than a boon but this version affects everyone fairly.
light i think would be interesting if it provided additional attacks when you're wielding it based on your base number of attacks, death of a thousand cuts sorta thing for 'weaker' weapons, with 1-2 attacks you get +1 attack and 3-4 you get +2, so a fighter with four attacks using two weapon fighting would be able to make a total of 8 attacks in a turn! (4 from the attack action, +2 from light, 1 from the offhand attack and +1 from light on the offhand)
edit: actually the additional attack on the offhand might be pushing it just a little, especially at lower levels.