I've considered swapping weapon initiative modifiers for an attack modifier equal to half their value.
This comes from the school of thought also represented in The Riddle of Steel RPG that weapon size and speed is a factor in being successful with your attack, not in your personal initiative. This also works well with actions that are not weapon related (yet normally your weapon plays a large part in your initiative whether you'll attack with it or not, when we don't use an action declaration round before initiative anyway).
Any thoughts whether that ratio sounds about right? The idea is not to necessarily have a fair deal for huge and heavy two-handers, as this shows that they're a bit unpractical for personal combat - but very useful in many situations, still. The sweet spot probably somewhere between the longsword (not the fantasy kind) and the katana.
I think if you go down this route you may be crippling Weaponsmasters etc that use the bigger weapons when compared to Tao.
Let's take a Tao at.. let's say Level 5. He get's a +20 to speed for using Unarmed Combat.
Now we take a Weaponsmaster of the same level using a Two-Handed Axe. Irrespective of the fact that he's possibly also wearing crazily heavy armour, his weapon alone gives him a -70 to speed.
The difference is 90 points. If you convert that to an Attack value, as per your suggestion, you're looking at an Attack difference of 45 points. Which is the equivalent to 90DP of Primaries. Or nearly two levels.
It becomes like a Level 3 Weaponsmaster is fighting a Level 5 Tao, and we can guess how well that works out for him. He's getting destroyed.
Using (very) rough figures....
The Tao's getting initiative 50% of the time (assuming equal armour, Dex & Agility). On those 50%, he's hitting the WM 50% of the time (sometimes damaging, sometimes not), and the WM is now on the defensive, so doesn't get to attack. So the Tao's at 25% hit percentage already.
When the WM gets initiative the other 50% of the time, or in the 25% that the Tao gets initiative but doesn't hit, the WM is hitting about a quarter of that time, because the Tao finds it so easy to block the guy's penalised attack. So he gets about 19% hit percentage. But that's ALL he's getting. In the other 3/4rs of that time, the Tao is getting to attack, often with a counter-attack bonus due to his block being so much higher that the WM's attack. So we'll say he hits 60% of that time. That's overall an additional 23%. Taking his total hit %age to 48%, compared to the WM's 19%.
Now assume you invest extra DP in attack at the expense of defence. The Tao's defence is not quite as dominant as it was, but now his attack is dominant as well.
The Weaponsmaster is getting hosed.

I honestly think the initiative/weapon-speed system is one part of the system (one part of MANY) that really does work well.
Of course, that's what houserules are about. If that's how you want the game to play, that's your prerogative.
I've also considered weapon reach as an extra complication, between 1 to 5, with the difference being a negative modifier for your attack roll times 5 (if your weapon is shorter, or if your weapon is longer and the opponent has closed the distance by succeeding on a strike or otherwise maneuvered in).
I think this is making the attack round a whole lot more complicated. I absolutely see the logic behind it, but I think you're making a lot of work for yourself.
Also, you'd need to start factoring in Size as well. Because how much reach advantage will a child with a bastard sword have over a Jayan with a short-sword? It's debatable.
My group's houserules:
1) can take up to 5 disadvantages, for no more than 6 CP
2) inhumanity level 3 required, zen level 7 required
3) Tao's cannot take "exclusive weapon" Disadvantage
4) Velez has a requirement of Expert Tai Chi AND Expert Kung Fu
Looking at them one-by-one:
1) This can make your characters EPIC. You're effectively saying you get up to 9DPs worth of advantages. That's pretty huge (but I'm sure it plays awesomely).

2) Fair enough.
3) That to me is a no-brainer. I hadn't even realised they had that option. I absolutely agree that Tao's should never be allowed that disadvantage. Unless.... they're using one of the weapons listed in DE that work specifically for certain MAs and not for others. That way, they're limiting what MAs they can buy. But never, EVER allow it for Unarmed. That's just a free CP usually.
4) Well that kills at least one of my characters off.

Low-level access to Velez is a godsend for MA-types.