So, on one level, we have Diomedes kicking ass, and we’ll get back to the main man after this, but first we have to deal with a subtler battle. Who is the better god of war? In the red corner, we have Ares, God of War. In the gold corner, we have Athena Goddess of Wisdom (and war, and crafts, and a few other things).
Since Ares only has one specialty, it would be easy to think that he’d naturally be better at it, and he’s quite good at laying waste to people on the battlefield. But the Greeks are also commenting on the nature of warfare when it comes to the Iliad. Ares has no finesse, he’s waded onto the battle field and killing the enemy, indiscriminately.
Athena, however, is much more precise in her targets. She wants Diomedes to keep an eye out for Aphrodite and take her out. After that, it’s all about Ares. This is good tactical sense, using her best resources against the enemy’s strongest warriors. Before Diomedes confronts Ares, the Greeks “always backward / gave way, as they saw how Ares went with the Trojans” (V 700-701). The god is just too much to stand against and will eventually demoralize the Greeks to the point of full retreat if left unchecked. Areas must be dealt with, and it will take the best the Greeks can send against him, which is Diomedes. Not Achilles.
Diomedes could have done the same thing, waded into the fight in a different place to simply massacre the Trojans, but this would be tactically unsound. Though battle lines fluctuate back and forth, they don’t often bubble. Armies give ground as a whole because bubbles can be cut off from the rest of the group and destroyed (what should have happened to Jon Snow, don’t get me started).
In order to win, Ares must be dealt with so that the entire army can progress. Athena’s choice is clear. Zeus even knows this as he “set[s] against [Ares] the spoiler Athene, / who beyond all others is the one to visit harsh pains upon him” (V 764-765). With just these few words, it’s clear that the better god of war is the goddess Athena. Ares makes war through the use of overwhelming force in either raw ability or numbers. There is no finesse to his fighting.
As the goddess of wisdom, Athena’s game is nothing but finesse. She could have chosen to do like Ares. She could have taken the guise of some Greek warrior and led a direct battle against Ares, but this was not her way. Instead, she stood by Diomedes and let him bet the one to challenge and dispatch Ares.
I don’t know if she could have taken on Ares directly because that’s not her way of war, it’s his. As the goddess of wisdom, she is deliberate in her actions, which are often not direct. She confronts him in her way, indirectly, wisely, and with the best warrior the Greeks can offer, whose only talents for direct battle are enough (with a little lean-in from Athena) to drive Ares away.
In a very real sense, this is an evaluation by the Greeks that tactics and strategy in battle will always win out over blind force. This will later be borne out as the Greek victory comes from the deception of the Trojan Horse, an indirect strategy as opposed to open warfare.
Athena is, by far, the more deadly of the gods of war. Superior tactics and strategy will overcome even armies of greater numbers and strength. Diomedes’s defeat of Ares on the battlefield demonstrates this understanding.