A clock stopped—not the mantel's
Geneva's farthest skill
Geneva = Swiss watchmaking, the world's best. Even the finest clockmaker can't fix this particular stoppage.
quivered out of decimals
Moving from measured time (decimals, fractions of seconds) into timelessness. Death exits the counting system.
pendulum of snow
Snow = cold, white, still. The body has gone cold and motionless like a stopped pendulum.
Decades of arrogance
The clock's hands keep their haughty positions while the dead person can't respond. Time itself is indifferent to individual death.