It doesn't require a True Rune. Luc had to overpower the bearers to allow him to be able to strip their powers. It is not like the bearer is going to simply sit there and let him use a Sindarin technique to take their True Rune. He needed to exhaust them first and then use the technique.
Actually, we don't see how Luc takes Sasarai's True Earth Rune. We see Sasarai crumpled over in pain and the next thing we know his True Earth Rune is in a container if I recall correctly.
Just because its fanatasy, a lion isn't a duck, and a beaver isn't a person. They have thrown in unrealistic things, but they have not changed things that already exist. So my rationalization about the conatiner being...well...a container, is correct.
You are missing the point of that statement. Those containers are not simply used for storage. You are trying to limit what the containers can do simply by definitinion of what we would call a container, but this is not evident in the game. As we saw in the game, the container can do much more than store things. It composed the materials of what Sasarai and Luc were made out of and it allows a person to use the powers of a True Rune without bearing it as well as double as a function of a container. In essence, it is a vessel much like Sasarai and Luc with much more capability than...well..uh..a container. So, your rationalization is only partly correct.
Why would Hikusaak go through the process of obtaining those containers and that technique if he could simply walk up to another True Rune bearer and strip their powers with his own True Rune? He already knew how to store True Runes in living vessels, why the need for that Sindarin technique and those containers if he could create living storage facilities? Obviously, the containers served more purpose than simply storage. Maybe, just maybe, they were necessary to obtain the True Runes he could not bear himself.
Again, look to my previous post. You have no proof or even logical sense to your statement. My idea of a True Rune drawing out another is much more plausible. He could have stollen Sassari's True Earth Rune without the containers, but the Rune would then be in limbo, and most likely return to Sassari. The containers acted as a simple vessel to withhold said rune.
What are you talking about "sense" for? How does your idea of a True Rune calling out another one make more "sense"? And it is simply not more plausible at all. First of all, True Runes have been shown to have their own agendas and a craving to choose their own bearer to achieve their individual desires. Now, try to think about this for a second, why would another True Rune listen to another and become subservient to it when they are all equal in power (which has nothing to do with the bearer)? Why would a being of equal power allow itself to be taken and controlled by another being without some other added outside influence? All logical evidence points to Luc weakening his opponents first, which we see on numerous occassions, and then him calling on the vessel which subdues the opponent, strips the bearer of his True Rune and then stores it for safe keeping (yes, the container does have a storage function which I have not denied).
Furthermore, there is evidence of even special runes protecting its bearer from the power of a True Rune. Example, the Bright Shield Rune protecting Riou from the power of the Blue Moon Rune while he was nearly unconscious and had half the power of the Blue Moon Rune. Another example, the Night Rune nullifying the powers of the Blue Moon Rune so Viktor could fight evenly against Neclord. Why not simply use your True Rune to strip the other rune from the bearer, kill the bearer and not even be bothered with them anymore?
If it is as you say, here is the scenario, Luc simply strips the True Rune, the bearer is stunned which we see occurs after the True Rune is stripped, he kills them and even without the container, if there is no living bearer to come back to then the True Rune will simply fly off, bury itself, or go onto the next bearer, so there is no threat of retaliation. Yes, we know Luc had other agendas aside from simply killing off the other bearers, but again, based on the evidence from past games we can see that simply using a True Rune to strip another True Rune is not possible (see Windy in Suikoden 1).
Why wouldn't Yuber, Neclord and Windy combine their powers to take the Soul Eater if it were possible for True Runes to strip a True Rune from a bearer? I mean, that is essentially what you are saying Luc did right? Windy knew how to bear two True Runes and she was much more knowledgeable than Luc and more powerful than Ted and Tir and had an opportunity (Seek Valley) to take it.
It just does not make any logical sense, as you say, to argue based on the evidence shown in previous games to show that one True Rune is able to be used to strip a True Rune from another bearer without something else involved. As we witnessed in Suikoden 3, the Sindarin technique and the containers are pivotal for the purpose of stripping a True Rune and not the power of the True Rune itself. Luc using his True Rune and the other true Runes just allowed fo rhim to weaken his opponent to the point where they could not resist the power of the Sindarin Technique, which is the container by the way.