Direct to the point.

How can I put 3 good skills in 1 weapon?

For example: SPEAR = Water Dragon Spear VI, Water Dragon Spear V, and Ice Blossom.

I tried to use some of my skill cards and my lunge step IV has been stocked by my thunder crack VII.

Any tip? ^_^

1º try again, because the skill cards replace randomly between the abilities [high risk-reward RNG]
(the 4º and 5º slot only can be used by Ougi skills)
2º drop more duplicates of the weapon [safe RNG], and those that are not good, use them in "Smelting"
3º buy on who did the combination which you wished [buy the lucky of the others]