NIKE

// Lava Lash
           if (m_spellInfo->SpellFamilyFlags2 & 0x00000004)
           {
               if (m_caster->GetTypeId()!=TYPEID_PLAYER)
                   return;
               Item *item = ((Player*)m_caster)->GetItemByPos(INVENTORY_SLOT_BAG_0, EQUIPMENT_SLOT_OFFHAND);
               if (item)
               {
                   // Damage is increased if your off-hand weapon is enchanted with Flametongue.
                   Unit::AuraList const& auraDummy = m_caster->GetAurasByType(SPELL_AURA_DUMMY);
                   for(Unit::AuraList::const_iterator itr = auraDummy.begin(); itr != auraDummy.end(); ++itr)
                   {
                       if( (*itr)->GetSpellProto()->SpellFamilyName==SPELLFAMILY_SHAMAN &&
                           (*itr)->GetSpellProto()->SpellFamilyFlags & 0x0000000000200000LL &&
                           (*itr)->GetCastItemGUID() == item->GetGUID())
                       {
                          m_damage += m_damage * damage / 100;
                          return;
                       }
                   }
               }
               return;
           }
           break;

maybe use

  
 SpellEntry const *spellInfo = sSpellStore.LookupEntry( triggered_spell_id );
if(spellInfo->AttributesEx3 & SPELL_ATTR_EX3_REQ_OFFHAND)
       {
           Item* item = ((Player*)m_caster)->GetWeaponForAttack(OFF_ATTACK);

           // skip spell if no weapon in slot or broken
           if(!item || item->IsBroken() )
               return;

           // skip spell if weapon not fit to triggered spell
           if(!item->IsFitToSpellRequirements(spellInfo))
               return;
       }

Lava Lash is working if you have an explicit Off-hand weapon equipped, but it does not work with One-hand weapons.

This is the way it should be? or One-hand should do the same work?