This is an odd one I came across in the last couple of days. I haven't noticed it before, but I don't usually hunt stealthy creatures that have the ability to successfully hide on me. If a creature successfully hides while I'm aiming a loaded weapon at them I get the usual 'you can't find them' error message. However, the next time I try to fire it at a valid target (usually another creature in the room without the aim bonus) I get a "That weapon must be in your right hand to fire!" error message despite it being in my right hand. Firing another time after that works correctly, so it's just a temporary error.

[fire]: aim
[fire]: circle
You begin to target a river sprite.
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You fake a river sprite, first moving one way and then another, leaving it off balance.
[You're nimbly balanced and have slight advantage.]
Roundtime: 3 sec.
R>
Learned: Tactics

>
* In a weak and directionless display of aggression, a river sprite claws at you. You dodge, leaping aside.
[You're nimbly balanced and opponent has slight advantage.]
>
Learned: Evasion, Shield Usage, Defending, Light Armor, Chain Armor

You've gained a new rank in maneuvering with a shield.
You've gained a new rank in maneuvering in light armor.
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Pulsed: Shield Usage, Light Armor, Chain Armor, Defending

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You feel fully prepared to cast your spell.
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You think you have your best shot possible now.
> [fire]: fire
A river sprite grins triumphantly as it completes its song, revealing a set of wickedly sharp teeth.
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I could not find what you were referring to.
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You do an impressive backflip, a smirk on your face.
>
A river sprite grins triumphantly as it completes its song, revealing a set of wickedly sharp teeth.
> [fire]: fire

>
You turn to face a river sprite, leaving the river sprite on your flank at melee!
That weapon must be in your right hand to fire!
>
* As if effort and skill were a bad thing, a river sprite claws at you. You block with a metal target shield.
[You're solidly balanced with no advantage.]
>
Learned: Evasion, Shield Usage, Defending, Light Armor, Chain Armor

>
Pulsed: Parry Ability, Small Edged

>
The river sprite leaps from hiding and ambushes you, but you are not surprised.
* Awkwardly, a river sprite claws at you. You block with a metal target shield.
[You're solidly balanced with no advantage.]

>
Learned: Perception, Evasion, Shield Usage, Defending, Light Armor, Chain Armor

* As if effort and skill were a bad thing, a river sprite claws at you. You evade, leaning just out of harm's reach.
[You're solidly balanced with opponent in good position.]
>
Learned: Evasion, Shield Usage, Defending, Light Armor, Chain Armor

[fire]: fire
< You fire a crossbow bolt at a river sprite. A river sprite evades, ducking in the nick of time.
The crossbow bolt lands nearby!
[You're solidly balanced with opponent in good position.]
[Roundtime 1 sec.]