I'm quite frustrated with the disarm mechanic in Baldur's Gate 3. It seems that after being disarmed, you can't immediately re-equip your weapon from the ground. Instead, you have to pick it up, which sends it to your inventory, and then equip it from there.
And there's also some sort of odd "disadvantage because you got disarmed at one point" debuff, so you can't even switch to your other set and change tactics on the fly.