Riddles

[mneme]

[edits: credit added where it's due, and typos fixed]
I appear to be in a riddle mindset today, so you all get the "benefit." Two of these are very specific propper nouns, one is the more common sort of riddle:

I killed myself to make myself, and avenged myself shortly after.
He who wields me, built me, yet he is far younger than I.
I serve are those whom I was made to kill, and have done so since my birth.
What am I?
[answered by bigscary]

I drank from a king.
Yet kings have striven to drink from me?
What am I?
[first answered by bigscary]

Hermes's silver snake,
I speed but do not slither,
Burrow but do not dig.
What am I?
[incompletely, but correctly answered by nightface

Comments

[batyatoon]

Shouldn't the subway train be "Hephaistos's silver snake," though?

[mneme]

Hermes scans better; I was thinking speed (and knowledge), rather than construction.