By the finite partitioning principle I mean the following:
Every infinite set is the union of pairwise disjoint finite sets all larger than 1 in cardinality. In other words every infinite set can be partitioned into a family of non-singleton finite compartments.
Formally:
$$\forall \operatorname {infinite} X , \exists Y: \forall a,b \in Y (a \cap b =\emptyset \land 1 < |a| < \aleph_0) \land X=\bigcup Y$$
Is this principle equivalent to $\sf AC$ or some known weaker form of it?
It is vastly weaker than the axiom of choice, since it follows from $X+X=X$ for any infinite set $X$.
To wit, take a bijection between $X$ and $X\times\{0,1\}$, and then simply look at the partition into pairs that is induced by the bijection.