Anyone that has attempted to make and upgrade Redhelm Arzuros armors knows how annoying it is to obtain Redhelm Ragehairs. They have a 70% drop rate, but ONLY if you break the Redhelm's head. This task can prove as frustrating as breaking a Rajang's horns, since like a Rajang, they have a high break resistance, and are often blocked by the Redhelm's bulky arms. As such, many Redhelm Arzuros die before their crests can be broken.
Fortunately, I have found a tried-and-true method of breaking a Redhelm's crest repeatedly and reliably. It requires a specific skillset, and one specific item, but if done correctly, this will yield you as many Ragehairs as you'll ever need.
Before I start describing the method, I'd like to mention that this farming technique is best done solo. My reasoning for this is simple: multiple people targeting a single, rather small point on an already smaller monster leads to a lot of tripping, which limits the amount of damage you can deal to the monster's head, and thus slows the breaking process.
For this method, you will need to have the skill "Partbreaker" on your currently-equipped set. This will make the head break faster (theoretically twice as fast as normal), allowing you to break it successfully long before the monster actually dies. In addition, you will need to bring a Shock Trap (not a Pitfall Trap. The reasoning for this will be explained later on), as well as a weapon with silver sharpness, and plenty of whetstones. Style-wise, I find Aerial style to work best for reaching the Redhelm's head, so it is recommended highly.
STEP 1: Take and start the quest "Redhelm I: Hunt". The Redhelm will spawn in Area 2, so head there. Spam Aerial vaults off the Redhelm so as to best hit the Redhelm's head and arms (only when it is safe to do so, though). It should be noted that without Mind's Eye, any sharpness level under silver will bounce directly off the Redhelm's arms (except when airborne), so keep those Whetstones handy for when the Redhelm flees the area.
STEP 2: Once the Redhelm's arms break, it should have taken a significant amount of damage to its head. At this point, place the Shock Trap you have brought, and lure the Redhelm into it. The reason you should bring a Shock Trap instead of a Pitfall Trap is because while the Redhelm is in a Pitfall Trap, it will continue to struggle, making the head harder to hit. A Shock Trap, on the other hand, will keep the Redhelm almost completely still for its duration. While the Redhelm is trapped, target only the head until it breaks.
STEP 3: After the Redhelm's head breaks, it should be near death, so make like Mortal Kombat and FINISH HIM!!!
STEP 4: Once the Redhelm has been slain or captured, check if you received a Ragehair in the rewards. If you did, great! If not, oh well. Rub, rinse, and repeat until all desired Ragehairs have been obtained.
Happy hunting guys! Hope this helps.