'"wear a lot of metal" or "carry a big freaking shield"' Actually, that's only really true for arrows and a couple of thrown projectiles. It's quite noticeable historically that after the popularisation of the greatest of all ranged weaponry, the firearm, shields and metal became nearly useless overnight. After that tactics and having a longer range weapon than your opponent became more important. Though I guess you could argue by the first world war and the birth of the tank things had swung back round in favour of wearing lots of metal.

Bucklers are parrying tools, and considering the character is a ninja-archetype (I'm guessing here, but throwing knives, very light armour and such tend to suggest this type of character) it would be a criminal waste of a free hand that can be lobbing knives and whatnot to waste it holding a buckler. 

In a combat sense a helm would certainly be useful, but awfully conspicuous. They also tend to reduce visibility, make stealth near impossible and otherwise make for an ill-equipped scout or acrobat or particularly a spy. 

You're right about the sword though, an old fashioned one handed blade of that kind would be more appropriate than a longsword, but the wakizashi-style blade Luminosity settled on is probably just as good if not better. 

Interesting points regardless.

To clarify, I do believe the best option the character has in its current format to protect themselves from ranged attacks is to close effectively using cover and once at suitable range just start throwing knives willy-nilly to offset their opponents aim as they close to melee range.