Notes from author
Leo ring does work with gargoyle halberd - it was originally intended to be a thrusting weapon, but was changed to a slashing weapon at the last second. FROM changed its damage type, but forgot to remove its ability to score counter hits.
Slashing halberds get an additional damage multiplier if you manage to hit with the "blade" or "end" of the halberd rather than the pole; this multiplier stacks with the two-handed multiplier, the counter multiplier, and the leo ring multiplier, tending to result in absurd damage. I have hit for over 1000 damage with 2HR1s in pvp with this setup.
Playstyle: I recommend you play through the entire game at least once using only the gargoyle halberd for a weapon to train to use it in pvp. Getting a good understanding of its reach, as well as how to get counters with it, is critical. In pvp, spam kicks and use well placed 2HR2s to keep enemies from backstab-fishing you. (seriously, SPAM kicks. I even recommend you train between invasions to learn to repeatedly kick without accidentally throwing attacks in.)
Now get out there and midroll. It's time to show those light-rolling and ninja-flipping scrubs what's up.