I wasn't aware of Aisha's sword having any particular magical property.
Bell's was appraised to be useless until he held it - then it becomes something essentially indestructible as well as allowing mana channeling - it it in and of itself didn't allow Bell to use any magic that he did not already possess.
I can't remember what his green slender dagger was about.

Welf's weapons are limited use spells that also act as weapons (presumably - though using them as one might ruin their durability - for example, using the nearly-shattered fire weapon he had to attack might shatter it prematurely). They seem to allow anyone to use them to the proficiency crafted by Welf.