First opponent I killed this run with blood rose pants equipped was a Third Eye Ganger, which gave:
You catch the thug with a burst of polysteel pellets for 15 ranged damage.
The thug slams into you and deals 3 melee damage before you can fend off the attack.
You catch him with an explosive round. It deals 19 ranged damage.
You extravagantly flourish your bone gun and fire it at the thug for 22 ranged damage.
You've won the battle! […]
The blood moves and flows, driving you onward.
You've gained 10 duration of Swaying Blood.
So seems some enemies give more than others. Discussion above seems to agree.
EDIT: 4 turns later I killed another Third Eye Ganger and got 4 turns of Swaying Blood, which brought my total up to 10 Swaying Blood. Seems consistent based on the total turns you have.