The fastest way to break this rod with zero fishing skill is to fish at the small greenish ponds at I-9 in the Labyrinth of Onzozo with Little Worms
(which can be purchased for about 4 gil from any of the merchants listed here), or Peeled Crayfish (which can be purchased from the Fisherman's Guild at C-8 in Port Windurst).
From an old fishing guide i have, hope it helps those of you looking for a way to skill up cheaply, but you might want to bring more than one to break because if you loose it your trip is over...
You can break a Mithran Fishing Rod fishing up logs with a Fly Lure in East Ronfaure's Cheval River (fishing skill is required to be high enough to at least drain the fatigue of the log, otherwise your line will snap and you will lose your lure) or in Kazham (with low lvl fishing skill + terrible feeling + monster music) or (Something caught the hook!!! You're positive you don't have enough skill to reel this one in!). Mithran Fishing Rods can also be broken in any of the pools in the bottom floor of Gusgen Mines by using meatballs as bait.
Gusgen Mines using Meatballs was the route I took and with 0 skill. Once you get the fishing message of "you have a terrible feeling about this one" you know its gonna break if you bring down the stamina for reel. GL.
Resistance 7/10.
Seems to have same resistance than Halcyon, but despite the description, it will break on many non-stackable fish (when you have !!! at the end of feeling).
Choose a Halcyon rod instead.