Unless those warriors are MI(Monstrous Inf), they can support with just one attack, no matter how many they have it. If they are, they can support with 3.
So, IF he manage to have 4attacks per model, in 5x2, he will have 25 attacks.
But, don't worry. Additional weapon means no shield, and frenzy means baiting. They hit hard, but suffer same. Str 5 is laughable for DKG. And for 460 points you can field 6 DGK, with full command, and steel banner. Or 2 regiments of 3, both with full command, but with no banners. AS 1+ wins against those, no matter how many attacks they have.