As a follow-up to the story of Akiva and Moses, I first want to share some of the traditional commentary that Artscroll includes in its Schottenstein Edition of the Talmud Bavli:
Commentary to tagin:
Rambam writes in the introduction to his commentary on the Torah that all the world's wisdom, physics and metaphysics, science and mysticism, are contained in the words and letters of the Torah, in their standard and anomalous shapes, in their tagin and points, and in their allusions.
Generally speaking, the Talmud and Midrash do not cite expositions of tagin. However, there is a Midrashic work, Midrash R' Akiva ben Yosef (found in Otyar HaMidrashim), that contains many such teachings, of both Aggadic and halachic natures.
Commentary to "[Moses'] strength ebbed"
Moses did not recognize the mode of Torah discussion that was taking place between R' Akiva and his students. Although the premises of the discussion were based on traditions from Moses, as the Gemara makes clear immediately, yet R' Akiva and Moses approached knowledge of the Torah in fundamentally different ways: Moses grasped the Torah through prophecy and an internal comprehension that was a result of cleaving to the Divine, not through an external intellectual analysis, which is the lot of later generations. Any novellae that R' Akiva, and his students arrived at were known to Moses, but they were in a different language of the mind and heart. Hence, they were unintelligible to Moses.
Commentary to "[Moses'] mind was relieved"
Moses was relieved when he realized that what R' Akiva was saying was based on a tradition handed down from him (even though Moses had not, in fact, received this tradition yet. This was not an issue of pride; Moses was the humblest of all men (Numbers 12:3). Rather, he was relieved when he realized that R' Akiva's external mode of Torah study leads back to the same internal understanding of Torah that he had received from God.
[It is clear from R' Akiva's reply that all of the halachos that he was teaching indeed derived from the Torah received by Moses. Those who would deliberately misinterpret the Gemara and attribute Moses' lack of understanding to "innovations" that were supposedly made by R' Akva are not only heretics, but are proven wrong by a careful reading of this very passage.]
Commentary to "meat market"
R' Akiva was tortured to death by having his flesh combed with iron dombs (Rashi) [As a final indignity, the Romans sent the combed flesh to the butcher shops to be sold there.]
Commentary to "This is of My part"
Moses' inability to understand R' Akiva's torah is related to his inablity to understand R' Akva's fate. The Gemara states elsewhere that fifty gates of understanding were created and forty-nine were given to Moses, but the fiftieth gate was not. The decisions to give the Torah through Moses and not through R' Akiva and to ordain this death for R' Akiva were in the realm of the fiftieth gate, in the realm of God's thoughts. ["Thought" in this context refers to ideas that cannot be expressed in mere speech.] God tells Moses, "Quiet!" because a person is not allowed to explore intellectually that which he is constitutionally incapable of understanding (see BT Chagigah 11b-12a, 13a). This boundary varies for each person and a person can broaden his intellectual horizon, but there is always a point beyond which a person will force himself into mental desolation. For Moses, this point was the fiftieth gate, and God reproached him to probed no further.