I encountered this bug too a couple of days ago on my first play. If I unequipped my original weapon for any reason, the game would refuse to let me re-equip it or any other weapons or shields. Nothing would stick in any of the weapon slots.
Was pretty devastated. Can’t play an RPG without being able to change weapons. Ridiculous.
So I decided to try a few things out, and I have some important info to share.
The cutscene where you throw your weapon to save Heodan is NOT the trigger for the bug. It also occurs in the Encampment, at the very start of the game.
First, I deleted all my buggy save files to start afresh. I did not reinstall the software. Started a new game on Normal, with a default male human fighter, all default settings. As soon as the game gave me control of him, I tried unequipping and re-equipping his stuff. He started with a sword and shield. It all worked fine. No problems.
So I went a bit further, threw my sword, then attempted to equip a spare weapon in the cave. Fine. No bug!
Great! So I made a new game with my proper roleplaying character. Set up all her features/attributes, etc carefully, the way I wanted them. Went into inventory at the first opportunity. Unequipped her sword and tried re-equipping it. NOPE. Hit the bug. Could not equip any weapons.
She was also a fighter character. But started with a two-handed Estoc.
So the bug is to do with your starting equipment. The Culture option in Character Creation is what determines this. My character was a FIGHTER from OLD VAILIA. This particular combination triggers the bug. I tried a couple of other fighter combinations with different cultures and they were fine.
I don’t know if there are other class/culture combinations that trigger the bug, I didn’t try every possible variation, but FIGHTER + OLD VAILIA definitely is bugged.
Please, devs could you fix this. It’s extremely disheartening to encounter this as a new player, it leaves a horrible first impression. It’s a fantastic game, but at least one class/culture combination is practically unplayable.