Vitality

As soon as Robin left the meeting, he went straight back to his house, 

bushing aside his ongoing research and setting himself and Zara on making low-level talismans.

In fact, Robin could now make much stronger talismans, the most powerful fire talisman he ever made reached level 17!

but they are useless in wars... 

Each talisman of them takes Robin about two weeks to make, within those two weeks he can make more than a thousand level 6 talismans! 

So on the grand scale, the less powerful talismans win by a sweeping margin.

The stronger talismans Robin decided to dedicate them to defend himself and his followers and maybe sell them if he needed money...

A level 17 knight's attack in the pocket... is worth a lot!

But they were not important on the grand scale of things, in two months he can make about 4 or 5 of those.. what would be their effect in a war that has hundreds of knights? nothing!