You can't assign variables directly to items as far as I know, no. Sorry, but you'll have to do it the hard/only way. Sort of say something like a $ITEMSTATE13 system variable (check my article on scripting items for more info, and we're assuming here that the sword is item number 13 in your storygame) and in this example if it's set to 0 then it means fighting bare hands and if it's set to 1 it means you have the sword in your inventory and you do more attack. There'd also be a variable for how much damage you do (%DAMAGE) and that'd be altered depending on whether you have a sword or not. And there's one for the enemy's health (%ENEMYHP).
IF $ITEMSTATE13 = 0 THEN
%DAMAGE := 5
ELSE $ITEMSTATE13 = 1 THEN
%DAMAGE := 15
END
Now for attacking you'd use this script.
%ENEMYHP := %ENEMYHP - %DAMAGE
That's the only way I can think of for doing it. You should probably get another scripter to go over this, I literally haven't scripted in almost a year now.