at 2 and 3, my ds liked to dress as cinderella, too, when his sisters were in their belle and ariel dresses.
at that time, we ordered the prince philip costume from disney, but it looked like a cheap bit of silver vinyl (uncomfortable looking and unattractive and not very disney costume worthy, imo), so we returned it.
my mom made my son a generic "prince" outfit: for a tunic, she used satin-y royal blue fabric and trimmed it with gold ribbon (basically one long piece of fabric with a hole cut in the middle to go over his head...so easy that even I might have been able to do it!). we found a shiny blue and gold cord to use as a belt. she also made a cape with the blue on one side and yellowy gold on the other side. this outfit still wasn't as appealing as the dresses, but it fit all of the preschooler criteria for attractiveness: "shiny", "fancy", swishy", and "twirly". to this day, i don't think my kids have seen any of the movies with the princes in them (sleeping beauty, little mermaid, snow white, cinderella...well, they've seen parts of that, but they don't like the stepmother), and when we read the books, i skip over the fight scenes/scary parts, so most "heros" don't play a big part in our lives, which is, in part, why the interest to be a prince isn't there.
we introduced the kids to robin hood befoer they turned 3, and my son really liked that, so he was robin hood (at almost 3 yo) for halloween (green shirt, black pants, belt, felt hat, and suction cup bow and arrow from $ store). THIS year they are ALL about peter pan (we've got peter pan, wendy and tinkerbell), but they've never seen the movie. tinkerbell treasures in MK is a GREAT option for a little boy buying "accessories"...my son picked out his peter pan hat there and the CM behind the counter made a nice little production out of putting the red feather in it! i agree with you about the weapons...we did get a plastic dagger for his peter pan costume (green shirt, darker green pants, brown belt), and i had REALLY mixed feelings about it. i actually wasn't even sure he'd know what to do with it, but my dh was captain hook for halloween, and my ds, our little peter pan, initiated a sword fight, so i guess i just have to accept his loss of nonviolent innocence! it's interesting, though, because unless we are all playing peter pan (i have a princess tiger lilly costume, so the whole family gets to dress up!), and dh is captain hook, he doesn't even think to ask for the little dagger (we keep it put away), thankfully!
good luck,