NO .5 slot shields as a hoplite or man at arms should never get a shield and lance and bastard sword in one package.
I maintain however that light lance, spear, double sided lance and that kind of thing should be 1.5 slot. You could say balance over length. It would be more acceptable for bamboo spear to become 1.5 than ash-wood pike wouldn't it? I would leave decisions like that to the devs and hope they do the right thing by the community. The purpose is to open new pathways in character design and to try to make the game better.
Remember if x-bows, hybrid-archers and hybrid-cav become a larger threat it in melee polearm and 2H will suffer without any mechanics changing.
Kafein did not suggest 0.5 shields, but 1.5, as an intermediate stage, compared to the current 1 to 2 jump.
I think the bamboo should stay at 2 slots (very long), not sure about the other ones.
x-bows hybrids would probably not be more effective since I don't think any crossbow would go under 1 slot, and I am not sure about how many slots per quiver of arrows/bolts.
hybrid archer's biggest problem is not the slots, but the need to sacrifice most of their WPF and many skill points for this (instead of 18/21 go 15/21 or 18/18 for example).
Hybrid cav would have to adapt. The heavy lance should go to 2.5 slots, the lance stay at 2 and not sure about the other ones, and we would be preventing them from getting a secondary top tier weapon (2.5 slots), which would harm them. They could however go for a worse lance and get a better dismounted weapon, being able to get a 1.5 slot light lance and a 2.5 top tier dismounted weapon (though no shield). Its all about the balance.
As I said before, choose either great at one thing, or good at two (lancing on horse or on foot in this case) (well, or mediocre at 3, or even worse at 4, etc).