Fallout 2 weapon glitch?

[SevenInchPancake]

I'm using the steam version with HR, other than that no mods or anything else;
In my latest run, my character can't seem to use a shotgun or a hunting rifle (melee weapons and pistols seems to be working just fine tho);
After equipping a shotgun/hunting rifle ,the UI looks like this:

What's causing this issue? And how do I fix it?

 

[NovaRain]

You can't use 2-handed weapons with a crippled arm. Check the manual about info and statistics on the character screen.

 

[SevenInchPancake]

You can't use 2-handed weapons with a crippled arm. Check the manual about info and statistics on the character screen.

thx!