This is simple. play as your prefered species ie elites! i hate elite slayer personaly but i think that just like H3 they should be in MM why not give em covenent equivilant weapons to?
They did this because they change the elite. Im pretty sure the jump higher in reach and plus the spartans use health packs and the elites never did.
The covy weapons are bassicaly equivilant except for needler. Plasma weapons do better damage against sheilds and non-plasma weapons work better against health. So both are equal enough in most the weapon calsses.