Going to job 50 allows for a merc to take mammonite really easily into his blacksmith or alchy career too tho.
My old battle blacksmith/whitesmith didn't worry about vending, you can always make a vendor slave for that. You want your battler to be the best it can be I suppose is the way I look at it.
Merc Skills on my old Blacksmith:
Enlarge Weight Limit-8
Pushcart-10
Discount-10
Overcharge-10
Mammonite-10
Item Appraisal-1
However even going to job 46 is okay I guess if you are impatient, just take down the enlarge weight limit to level 5 and the item appraisal hasta go too. Well if you are willing to make a vendor slave later you can lower discount and overcharge levels even further to get yourself able to change at job 40.
What you haveta do as a BATTLESMITH however is remember you won't be a pure forger so you got to decide what you forge to make money off of. I suggest daggers be one of these, many classes can wield daggers *sins, alchies, rogues, and some blacksmiths and swordie classes utilize this option* and then another wep maybe. The reason is cause you have to get your battler skills too *fists and two handed swords seem popular too, but you might take maces or axes for yourself*
Well if you want to work yourself out a build here's a link :3
This is the skill planner site I use so have fun with it everyone!
http://web.hc.keio.ac.jp/~fk061999/himey...index.html