How much Zeny does he or she have to Spend?
Best is probably a DDTS comp Bow, or a DDT Sherwood. For this however you'll have to have a ron of Zeny. (the cards alone are worth 60 mill+ )
Low budget is probably elemental Daggers, for example: Use an Ice Dagger on High orcs.
Or, If you're getting a Weapon just for leveling, you could get a couple Orc lady cards, and put them in a Dagger. (+30% Damage to orcs I believe)
That would enable you to level well @ High orcs.
Or if you have IC gears, Get a 4x Drops Dagger for a Faster cast, and you can plagerize Stomgust, and mob High orcs.