Well I'm not making a sword so much as a bar of heat. Would it need a "hilt" focus item to come out of? To be tethered to?
And I disagree with their assessment that it's better to have a real sword. They're illegal to carry, hard to conceal and sometimes your bad guys don't let you keep your goodies.
Maybe in your mind. Mechanically in this game though, what I said is true. If you don't like that, you have 3 options.
1. Make it an enchanted item.
2. Model a lightsaber power after "claws" or "breath weapon" and make it an IoP
3. House rule in benefits for melee evocation over ranged and lasting effects over single exchange casting.
I'd recommend 1. Statting an IoP takes effort. Enchanted items are easy. Make it Weapon 4 and claim its uses are limited because it runs out of charge (which is essentially true anyway for enchanted items.
Id also read YS more carefully.