1) Picking up a weapon, or pulling an elevator lever, or whatever is movement. You may not have moved in meters, but you've moved. If you did it while engaged in melee you will still provoke an attack.
This is the easiest adaptation of the rules, and - I'm sure - the intended consequence of bending over in the middle of combat to retrieve a weapon. Interacting with anything while in melee (whether your hacking a computer terminal, unpacking a crate, using a control panel, whatever) should be considered movement - movement which drops your guard and affords your opponent a free strike.
I like the houserule of "scattering" the disarmed weapon by the degrees of success, but I think you can take it or leave it (I'm going to take it though!) - the real core is that picking up a weapon off the ground provokes an attack and is a half action. The half action is the "move" to get low enough to scoop up the weapon (assuming of course your acolyte doesn't have freakishly long arms hah).
I think then it's an additional half action to "ready" the weapon - meaning not just picked up, but picked up in the right orientation such that it useable in combat.
Quickdraw, as written, does not specific that the weapon needs to be on the character's person. In fact, it doesn't specify ANY range at all… but use your heads guys … if a weapon is 20m away, does that mean a character can ready it as a free action? So why do you think they could ready something at their feet (aka out of arms reach)? You can ready things for free that you can reasonably reach… and in that regard, I think you could "ready" the weapon for free, but it would still take a half action to "move" to the item at your feet (also drawing a free attack from your opponent).
Based on some of the new uses for acrobatics listed in the Inquisitor's Handbook, I'd also say you could use acrobatics to avoid the free attack (i.e. roll to the ground, grab the weapon, and spring back up - whatever).
So to summarize the benefits of a successful disarm using this framework of rules (which I really don't consider house rules, as their implicit in the core rules to me at least), against an enemy with:
> no special talents… he spends a half action to bend over, you get a free attack, then he spends a half action to ready the weapon.
> quickdraw… he spends a half action to bend over, you get a free attack, he readies the weapon for free and attacks you.
> quickdraw and acrobatics… he spends a half action to bend over, using acrobatics to attempt to avoid a free attack, he readies the weapon for free and attacks you.
… also note that when you get a free attack, he can't parry because he has no weapon in hand (assuming he wasn't dual wielding).