Epic Fight Guard Fix

Two-handed weapon + shield: don't lose the weapon's own guard

• With allowTwoHandedWeaponWithShield turned off (the default), simply having a shield in the offhand while wielding a two-handed weapon was silently disabling that weapon's own baseline guard/parry entirely -- not just the shield-combo bonus (stamina-free guard, penalty reset, passive buff) that setting is actually meant to gate.
• Two separate checkpoints needed the same fix: the guard-skill's own availability check, and (further upstream) the input handler that decides whether to even send a guard request at all -- a shield in the offhand was short-circuiting that request before the availability check was ever reached.
• Now a two-handed weapon guards/parries normally on its own, with or without a shield in the offhand; only the combo bonus stays gated behind allowTwoHandedWeaponWithShield.