There is a foe called "Metal Armour" and if it uses it spechal move, your equiped weapon/shield will be sent flying untill it hits a wall/foe.To prevent this, if you see it, un-equip you weapon shield, then if it trys to send it flying in the massage log it'll say this "Metal Armour knocked it! but nothing was knocked!"
hope this helps!
one of my BEST weapons was knocked but it said "Golden Blade+10 was knocked! Golden Blade fell and is unable to use."
so it fell but there was no room on the floor area i was in and it fell through the floor and was NEVER see again...