... any weapons beyond the 2 handed sword
will not equipt on my character.
Hey, when you've already achieved perfection, why keep messing around? ;)
Okay, in all seriousness: it sounds like a glitch, but... what race/class combinations do you have in your party? Only fighters, paladins, barbarians, rangers and larks can use magic weapons at all, and rangers can only use those up to +2.
Also, have you raised the strength of any of your front line warriors; and if so, by how much? It's been years since I've played, but there may be minimum requirements to wield certain weapons.
Last but not least [MINOR SPOILER]
there are weapons you can find (in fact, which you eventually must find) which are more powerful than the ones you can buy; and those weapons should be able to be equipped by anyone in your party.