I did a 10 minute test run using Ledmitz to test experience per minute and then average the results, while wearing the bull helmet. I lured all the male skeletons in the graveyard to the 'freezer' so that I could attack all mobs of the same type; Lady Skeletons. I did have to run to mobs in both 10 min runs, but made sure to follow the same path in both cases. Instead of relying on the client I recorded each min as it was reported and later averaged the results. I also excluded the first minute in both cases, to ensure all minutes were doing attack action and not idle.
I'll do this one in point form:
Level: 107
Skill: Speed
Stats: Str=80(70+10), Agi=90, Vit=60, Int=1, Dex=80, Luk=60(59+1)
Mob: Lady Skeleton
Exp/min (avg of 10 mins):
Beheader Sand Cutter
17782.2 17185.6
The beheader barely won out in this extreme build for use with the beheader. Had I distributed status points for the sand cutter, I believe a higher exp/min would have been possible and even higher using the rage skill with different stats. I had previously compared the 2 weapons using different builds with both rage and speed. Most always, the cutter yeilded a higher exp/min avg, but most often, then highest and lowest exp/min were obtained using the beheader. This makes sense though, since you need a higher level to use and even obtain the sand cutter, but using the beheader is very fun, as I find myself looking at the damage, looking for a jackpot or counting the hits to kill certain mobs. It can vary quite a bit.
The most interesting thing I found though, was that if you change the way you play, you can take less overall damage, doing hit and run attacks. Cancelling the attack each time before attacking again also seemed to help gain initiative more often and possibly, the mob hasn't time to attack.
This is a really fun weapon to play with, but isn't very reliable and you really need a super fast attack to make any use of it. Moreover, lower level characters needn't have strength to do damage with this, but will need a very high dexterity as it will probably hit less often than a n archer with a similar dexterity.
There I go nerding out again. If you test the same weapons and want to post, please mention equipment/stats/skill/level, as above.