I'm not sure where this comes from - I found it on a homemade motivator of Signum from Nanoha, on an Exalted site, unattributed - but as oaths go I really like it, even though I doubt it'll fit what you're after:
"I am your sword against all foes.
"I am your shield against all woes.
"I am, forever, yours."
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"V, did you do something foolish?"
"Yes, and it was glorious."
"I am your sword against all foes.
"I am your shield against all woes.
"I am, forever, yours."
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"V, did you do something foolish?"
"Yes, and it was glorious."