I do like this for the pledge, and while the math works, it can be simpler, and balance better with Medial and Medial, instead of 2 Lesser Tasks and a Medial Blessing.
Simplify it down got it!
How's this?
Attempt 2/5
So this I do say that as long as you and I speak truth so shall we stay hand, tooth and blade as we offer each other aid. For your time and delay be it we shall in the soil labour with ease without worry of growing weak in the knees. But till past the sun set hour should these bonds prove perverse, then sure failure shall be our curse.
Task: Alliance -2 (offer aid as necessary -- safety, labour, honest information/answers)
Duration: Day +1
Boon: Blessing +2 (Iron stamina at 2 dots)
Sanction: Curse -1