The logic is a bit wobbly, but are you...
I am one, but not the only one.
Unsure on this. Speed is a measurement, just like mass, force, and innumerable others. So one, but certainly not the only one.
If you deify me, I leave.
Godspeed is a somewhat antiquated alternative to "goodbye", so if you say it, someone's leaving.
If you do something else to me, I give wisdom.
Bringing someone up to speed means informing them regarding a situation.
If you take me, you are doing something that starts with me
If you "take speed", you're speeding up (and "speeding" starts with "speed").