Glad i can help Gem ^^ the best way i've gotten so far of grinding those annoying items is getting my lvl99 (in my case Ganondorf with Blades of Demise) and getting the weapon upgraded with Rupees+ and Materials+ this will always give at least a silver on those annoying bosses and sometimes a gold or a weapon. In the rewards quest specifically the one for completing True partners Illustrations (kill skultulas in legend and 2 in hard) you have 6 heros. Zelda, Agitha, Midna, Impa, Lana, Fi and Dark Link. You get to choose one of these people to have as your partners the other 5 will side with Dark Link and go out gunning for your head.
Not sure if it's been posted here or not. But the best way is with your Lvl99 slaughter the mobs in the starting area then in the keep nearby and the foes to the north and south depending on who's closer. If you have 3:20 on the clock go pick Midna as your partner (she is the strongest in defense) this then leaves 5 very easily slain heroes gunning for you. If you are fast you can take zelda out, then target agitha if you have your special charge wait for the others to show up. The order for me is Zelda, Agitha, Fi, Imp and then Lana. If the others are too close during the beating of Agitha then unleash your special it should take out both Fi and Impa if you are strong enough. Then just whale on the other two then run to Dark Link and beat him with your special or normal moves.
This generally nets me at least 2 weapons and normally a few silvers and 2 golds plus 40k rupees for completing and between 12-15k extra for killing foes.
Quickest way to win that battle and farm several of the heroes. It will take longer if you don't pick Midna but if you need her Drops i would pick Agitha as she tends to be almost as defensive and cause severe damage if you don't monitor fast enough