I believe you are somewhat mistaken about Silvered Weapons:
Some monsters that have immunity or resistance to nonmagical weapons are susceptible to silver weapons, so cautious adventurers invest extra coin to plate their weapons with silver. You can silver a single weapon or ten pieces of ammunition for 100 gp. This cost represents not only the price of the silver, but the time and expertise needed to add silver to the weapon without making it less effective.
Werewolves and fiends are resistant to non-magical weapon attacks that aren’t silvered. There may be more creatures that are weak to silver but those are two examples. Silver-coated weapons are not considered magical; it’s just that the creature they are hitting is weak against them.
However, you might be able to do this using the barbarian's Path of the Battlerager (SCAG, p. 121), though it's normally restricted in the Forgotten Realms only to dwarves.
Battleragers gain the ability to use spiked armor, described in a sidebar on the same page, as a weapon. The 3rd-level Battlerager Armor feature lets them use a bonus action while raging to attack with their spikes, and automatically do damage when grappling creatures.
And at 14th level, Battleragers get the Spiked Retribution feature:
Starting at 14th level, when a creature within 5 feet of you hits you with a melee attack, the attacker takes 3 piercing damage if you are raging, aren’t incapacitated, and are wearing spiked armor.
So if your DM allowed you to either plate your spikes or make them entirely out of silver, you could in fact hurt a Werewolf or Fiend with your armor. I would imagine the cost to coat or make the spikes silver would be very high.
So if you happen to be a Dwarf Barbarian Battlerager in a campaign that is heavy in Werewolves or Fiends, and you have a lot of gold, it would be in your best interest to plate your spikes with silver. Actually, it sounds like a lot of fun.