Well then: Ask your GM, as usual. (Or, if you're the GM, ask yourself.)
House rules are in-house, and that includes rules not specified in the book.
(If the book didn't say it, then priorities would be GM>Some guys on the street.)
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(I personally won't allow this though. You can just try it yourself IRL:
a)Hold a 3 kg weapon in fighting position.
b)Lower it but keep it in position that you are still in control.
c)Use one hand to open and then grab something from your pocket, in front of someone who wants to kill you.
So... There you go. It's about as troublesome as holding it one-handed as sheathing the thing, effort-wise.
Or the reverse,
a)Try to open and put something into your pocket with one hand, in front of someone who wants to kill you.
b)And then ready a 3 KG weapon in a way that is combat-ready. - Mind you holding a sword is different from weilding it as a weapon, otherwise you just made thousands of years of swordfighting techniques mooted.
Cause we're talking about common sense, right? Common sense probably won't have you keep your bag open in combat and spill everything. Or if you're using straps, to properly strap something down or releasing it isn't that easy.
But that's just me.
So, like I said, ask the GM.
This fast-switching rules tidbit have been around for quite a while actually.)
