You're right about the shape of the arm/stick. The difference in application (and terminologies) has to do with the angle against which you're defending. Let's assume that the attack is with the right hand and comes at a downward angle:
If it's a backhand, then there IS a point at which force meets force (due to opposing angles) but the oppenent's weapon will slide off your weapon as it is heading downward anyway. But you may need to reinforce your weapon by checking the hand or wrist or forearm - or you may need to collapse your weapon slightly and "ride" the force of the opponent's stick down - or you may need to buttress the end of your weapon against your shoulder. These are all variations of the same movement that end up differently due to slight changes in speed, or angle, or force of the attack.
BUT
If it's a forehand, then the point at which force meets force is actually quite incidental as the angle of your weapon is almost the same as the angle of your opponent's weapon; you don't need to reinforce or control the opponent's weapon so much as just get out of its way while maintaining a covering stucture. Passing the opponent's weapon with your live hand allows you to guide it into the structure.
In both cases, your footwork allows you to zone away from the angle of attack in the case of an angle 2 attack, toward the angle of attack in the case of an angle 1 attack (but you meld with the movement and contol it).
It's really your angling and footwork that allow you to do this - and I think that if you think of the stick as a blade the actual application is to the wrist or forearm of the opponent.
All this is of course "theoretically" - the best laid plans of mice and men etc.
The 3-part series of Kalis Illustrisimo with Tatang Illustrisimo, Tony Diego, et. al. has several examples of "Pluma": these are done against an overhead forehand attack. PM me and I'll send you some windows media examples.
Best,
Steve