I'd say an attack is hiltslashing if you do the move (right swing + left facehug or the opposite) and the attack connects so early you are forcing your opponent to block twice in a row.
If your enemy can do that, so can you; so if he can "pro" spam you, you need to try to enhance your style, aka : learning hiltslash too, mini-block+fast counter, chambers, better footwork, faster build/weapon, going in & out of range (the so called backpedalling and 180°)...
Everything that gives you an edge! Every tools that you are free to use in this game to become better!
The only argument I hear is : some of it looks stupid/unrealistic.
Tbh me too when I see some great "pro" moves being pulled, I dislike having to counter them, and do not like their "appearance", I dont use them and it makes me worse than I could be but I assume it. Like when your opponent looks to the ground so he can better conceal the weapons animations... sometimes they also feint/spam while being in stupid body angle position
But I know better not to ask to remove them.
Why ?
Because if you do, you lessen the high skill ceiling of cRPG and switch to a too predictable (with the actual game speed) classic duel with two guys facing each other and looking themselves in the eyes. That would look "cool" but the average cRPG players would block 99.9% of the hits correctly and fights would never end in a 1v1.
I would be totally for "nerfing" the hilt slashing so the "island" you speak of is much much smaller or harder to reach (the point where you connect early with 100% damage); but you have to understand that if it totally disappeared, you would have only two cases : glance or normal hit. If you would glance totally everytime someone gets a bit in your way or your opponent moves to your side, not only offense would be bad, but defense too.
Without hiltslash there would be a dire need for a faster gamespeed too, for the reasons above.
As I see it, from my full STR point of view, in duels its one of the "lame" trick move you can use, its as good in offense as in defense (to counter a faster opponent's weapon or footwork), but its also one of the few trick one can still use against ganking. With turn speed nerf it already dented a lot of the berserker rage I liked a lot, if hilt slash was to disappear you would have totally 0 chance of fighting more than 2 guys properly face hugging you.
Would be kind of an indirect buff to agi because they could get around you so you glance and not them (which is already the case a bit... damn GTX always get me this way
) which would be actually fair in the actual situation where STR dominate