That is not nailed down yet, but my basic idea is that you can have a bag or pack in which you can store a lot of things, but browsing inventory takes place in real-time. That is, if you have a throwing knife in your bag, it will take you a few seconds to get it out, so you probably don't want to do that in the middle of a fight. It also cannot hold more than it actually could. In many games you can store swords, suits of armor, and all sorts of crazy things in your pocket, but not so in L2.
On the other hand, you could strap a scabbard or bandolier to yourself for quick access to weapons. This would be useful in combat, but can also impair your movement.
