This is purely a CC weapon. The lights will cleave a ton of enemies and stagger them all or most of them. The lights will also stagger elites. Weirdly, it’s not shield breaking, but two heavies is enough to open up a shield-carrying enemy and a third will knock them down.
Other than the large horde cleave, the main thing that M+S/H+S has is its charge 1’s ability to stagger a CW even harder on even more than a shield push. Only overhead and uppercut will hit through a M+S or H+S heavy 1.
There isn’t much strategy against armour. You can do a couple lights for stagger (and some small damage with a headshot) and then follow up with heavies, or just spam heavies. Against shields, three heavies, or two and a push or push and two will knock things down. Lights when things are knocked down.
Finally, against CW, use heavy 1 to keep stun locking them. It staggers even harder than a shield push.
Actually 1h sword and shield is pretty decent against armour on a Mercenary built towards crits. That’s what I play when I’m not playing Dwarf. It plays differently and it’s really fun. The horde clear when buffed with Merc passive + attack speed on crit is excellent. Anti-armour is very strong on crit. Charge1 -> Charge2 -> push -> push follow is OK. Charge1 -> Charge2 -> Light2 -> Light3 is your strongest anti-armour combo and it’s really amazing. The only thing that really throws off 1h sword and shield Merc is shielded elites. Usually then it’s trying to hit a push followup crit headshot.
What I love about 1h sword and shield is how much nuance the weapon has. Light 1 and 2 have low range but good cleave so they will only proc Merc passive when you are facing a horde, but that’s when you need it. Light 3 is Kruber’s strongest anti-armour attack, but has no cleave to speak of. Charge 1 is a bash, charge 2 is Kruber’s highest-damage attack, with huge crit and headshot multipliers, but doesn’t do as much damage without either of those as his light 3 (edit: against armour). Finally, charge 3 has no armour pen whatsoever but has high cleave and range and will proc Merc passive outside of a horde. Push followup is a weaker charge 2 without as good headshot and crit multipliers that is pretty much only good against shielded elites.
You have to put it all together but when you do it all works really well and it’s super fun to play.