7.5-15% Weak Spot Damage. Weakspot Kills also ignore Enemy Hit Mass.
6.5-8% Strength for 3.5s on Hit. Stacks 5 times.
Ranged hits add 1-4 stacks of bleed to enemies.
Target receives 1-4 Stacks of 2.5% Brittleness on direct projectile hit. Debuff lasts for 5 seconds and can have a maximum of 16 stacks.
HS has some of the best cleave + horde clear out there and can one shot unarmored and flak armored elites pretty reliably. It's also fast and pretty safe to use defensively. I use the hs7 and loop h1 + special for mixed hordes, loop h1 + l2 for horde clear, or spam lights for groaners / pox walkers. PA, H2, and special can be nice for hitting a narrow target from the left like a bulwark peeking behind a shield. I almost exclusively use a bolter with it to allow me to magdump crushers and bosses since hsword is weak against them.
H1 is your bread and butter, sliding into combat while charging an H1 will let you rip the head off any enemy smaller than a mauler. If you're having difficulty landing headshots, you can swap deathblow for rampage, which sacrifices your ability to cleave through more heads of elites / chaff for a little more reliability with general damage + cleave output when not hitting weakpoints. Just remember you're doing a bit less damage at the start of combat and relying on rampage to ramp up while fighting.