Providing Arms to a Non-Beggar?

Is there any clear international law around this question of financing d providing of arms? It's actually, oddly blurry. There's at least two principles which are relatively easy to wrap one's head around at stake. And supplying weapons as a non belligerent means that you violate neutrality in the strict sense of the word. To impose a arms and arms embargo in a situation of massive asymmetry is effectively to take sides again.