Basically that's it.
The descriptions are generally too short and kinda topos-like. He wrote two case where he noted that fleeing enemy died in greater number. But in most case it feels like the rivers just engulfed them and they weren't the particular doings of the chasing armies (especially in the case of the first bloodless battle).
One more interesting part from Book III. It's funny.
Chapter X.
How the dust of that place prevailed against fire [After 642 A.D.]
pg. 157.
"About the same time, another traveller, a Briton, as is reported happened to pass by the same place, where the aforesaid battle was fought. Observing one particular spot of ground greener and more beautiful than any other part of the field, he had the wisdom to infer that the cause of the unusual greenness in that place must be that some person of greater holiness than any other in the army had been killed there."
Did this traveler find a shallow mass grave of human fertilizers?