Catching monsters?

[Rizzice]

I just got to the part in calm plains where I was introduced to weapons with weapon catching on them, or whatever.. how exactly do I catch monsters? I can catch any fiend or what? And what's the point? Just for rewards (what kind of rewards do I get)?

Is it really worth the time? Like should I keep my taming weapons on at all time?


ALSO: I reached this secret abandoned castle thing where I fight this summoner's summons.. is there any point in this too? I've fought her twice and the 2nd time all I got were some X potions..