I don't think the Medicine rune allows pitching anything other than Meds and Mega Meds, though.
UPDATE: Finally got a Wall Rune from SunKing with the Hunter Rune. According to my experiment, Tuta DOESN'T pitch Meds anymore when equipped with Wall.
The most likely to benefit from the Wall Rune are Knight Rune tanks with at least one rune slot available. This makes Miklotov the perfect candidate for a Wall Rune despite having lower HP and DEF than say, Humphrey, because of his perma-Knight Rune and a second rune slot at level 52, whereas Humphrey has only one.
While Humphrey can still equip the Wall Rune, he can't equip both Wall and Knight at the same time, so he can only protect Futch at low health with just the Wall Rune, unlike the Knight Rune which can protect ANYONE at low health from single-target physical attacks. The point is, Humphrey already has insane DEF to need a Wall Rune, so Knight would suffice for him.
I was able to determine so because Defending still permits the character to protect another from damage, as I have seen many times while doing the Matilda glitch. When I tried to level up Nanami and Jowy with this, I used to get annoyed at how they protect Riou at low health when I'm supposed to kill him off, even when they are defending.
It's not all about knowledge, but it helps.