sabre, sword, blade, clock hand
剣 centers on a double-edged cutting weapon: a sword or sabre. The clock hand sense is a metaphorical extension of a blade-like pointer.
剣 is the modern simplified form of 劍. The older form combines 僉 (which likely contributed the sound) with 刂 (knife), suggesting a cutting weapon. The modern left side 㑒 is a simplification of 僉.
The right side 刂 is a knife, and the left side 㑒 looks like a person with a mouth, perhaps shouting. Imagine a person wielding a knife-like sword, ready for battle.
For ケン, picture a swordsman named Ken practicing with his blade: Ken -> ケン, and his sword is always ready.
sword (esp. a large, double-edged one); blade
serious; earnest
kendo; Japanese martial art using bamboo swords
sword; dagger; knife; bayonet
swordsman; swordswoman; fencer
short sword; dagger; stiletto
(art of) fencing; swordsmanship
bayonet
shuriken; small throwing blade; throwing star
great swordsman; master fencer
sword dance
needle-point holder (in ikebana); frog
master swordsman; skilled fencer
point of a sword
treasured sword
divine sword (one of the three sacred treasures)
threatening attitude; menacing look; angry look
weapons; arms
bokken; wooden sword
bayonet