sword
劍 centers on a double-edged sword as a weapon. The meaning is straightforward: a bladed weapon used for cutting or thrusting.
劍 is the traditional form of 剣. It combines 僉 (which likely contributes the sound) with 刂 (knife/blade), forming a phono-semantic character for a bladed weapon. The modern simplified form 剣 replaces the left side with a simpler shape.
The right side 刂 is a knife or blade. The left side 僉 looks like a complex assembly of parts, perhaps a handle and guard. Together they form a complete sword.
For ケン, imagine a swordsman named Ken wielding this blade: Ken -> ケン, and his sword is 劍.