In Soulcalibur IV, it can be bought in Character Creation for 7,000 Gold after completing Story Mode with Raphael.
The Estoc gives a lot of HP (55) to you when equipped, but its attack power (110) is somewhat low by Soulcalibur IV standards.
A sword designed to pierce through an armored opponent. Resembling a giant needle, it has no problem shearing chain mail and can even penetrate plate armor if properly aimed. But because it lacks a wide blade, it is not good for defense.