They have relaxed the requirements for obtaining land battle skills in all 3 disciplines (weapon techs, trap techs, item techs).
You can get just about any tech at the end of any land battle (at least r1 and r2 techs).
I have personally gotten trap techs and weapon techs at the end of battles where I know the enemy did not use them on me. Item techs are harder to see since the game doesn't neccessarily tell you the npc's are using them, but sometimes you can see the graphic effect from it's use.
Unconfirmed, but I believe you stand a better chance of obtaining a tech if it was used against you.
Now we wait for somebody to come by and tell you that everything I said is a lie and you have to do it the old way or it won't work at all. ( 30000045 )
I believe it says r11 search on the colorado plateu just above your question. It does not say this however, I believe they can be manufactured at the craft shop in a colony as well. ( 00143900 )