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I don't think it's definite like that, but they have different functions. The drow knife throwing will be snipe from right hand and rapid throw from left for example. Lyranet installs from the right hand.
I use the right hand to cast regenerative spells, but it's also used with apan mudra turned outwards in front of the heart to drive away evil. The hideous spear goes in right hand, the Fay knife in left. I haven't thought to categorize them, they just have different effects.