The Reason I'm thinking there are 3 bonds specifically and not 16 or some other number is due to the nature of the cosmere itself and as a larger literary device. 3 Realms, 3 bonds, 3 parts to a god [the intent, command, identity]. We see 3 repeated throughout the books almost as much as we see 16 or other numbers related to the various gods . it seems to follow better then 2. if there are 2 kinds of bonds then why 2? if there were 16 bond types I would also accept that as a reasonable number that would align with the state of the cosmere.
The comment and WOB you used to comment on it being "connected to divinity" is exactly my meaning. this would be the Zahel bond. and I am assuming Nahel is also an alethi word. that would seem to point to this third bond and the bond being A Zahel Bond