I think he means being able to hit an opponents block and hit him again before the opponent can attack back. Also known was spam, which every class can already do. Which is not the same as a hiltslash though, which cannot be done by 1h.
I think the term hiltslashing is being used in very varied fashions nowadays, but when I say hiltslash I mean the borky rightswing which pretty much does instahits for way too much damage after doing an early angled leftswing at facehug range. You used to be able to do it with a ton of weapons as you can still do in Native, but in cRPG it has actually been made more difficult and you're going to need rather fast weapons. Still, it can be done by both polearms and 2h. Not by 1h though, I am pretty sure that whatever you do, a double leftswing will be faster than a combination of left and then right.
If the OP doubts the ability of polearm and 1h to spam compared to 2h, grab a quarterstaff or watch players like Atas or Jackie leftswing spam. That said, 2h is very easy to spam with due to ridiculously forgiving sweetspots.