I don't think it'd be too hard. Just add a switch within the saber's cog, to cause it to switch back and forth, depending on current state. If you want it to be so that if you switch away and back to it, that it's automatically on, you'll probably want to add a switch to check for previous weapon. Either way, I'm sure this is doable. I'd actually check into SavageX's FR mod, or SS3 mod, as he has multiple weapons on a number key, which would be related to what you want. A similar type of switching would be occuring.
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Wolf Moon
Cast Your Spell On Me
Beware
The Woods At Night
The Wolf Has Come
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Wolf Moon
Cast Your Spell On Me
Beware
The Woods At Night
The Wolf Has Come