Personally I'd rather have 30 Demigods than 8 with pretty looking weapon changes..
And have 20 weapons instead of 3.
Since, if there are 8 demigods, and 3 weapons, that's 24 weapons that need models/textures/shaders/effects if applicable.
After all, the Rook has a big hammer, it fits it. So presumably any weapon it gets would be a hammer. While this may have the same stats across all Demigods, same effects, same bonuses, itd appear on the Rook as Hammer. A Torch for the Torch Bearer.
Now 30 demigods, 20 weapons, that's 600 that need models/textures/shaders/effects if applicable. That's a lotttt of work.. I wouldn't expect that.
It'd be doable if you had hammers, staves, swords, daggers, and so on which shared between them and the models just scaled to fit.. But it just wouldn't look right. Some of those weapons just wouldn't fit being weilded by some Demigods.