how about giving rune fencers the option to buy runes like spells you buy the runes and they can only be used after you hit a certain level, you can equipt different runes for different effects and "cast" certain combinations of runes for different attacks, spells, or debuffs.

so say at lvl 5 I have 3 runes A B C

rune A> attack rune boosts attack
rune B> def rune boosts MADEF
rune C> Fire Rune attacks with fire

at level 10 you can link runes and/or get new runes for instance rune A+ rune C= gives your attack fire stat dmg while rune B+rune C= Fire Spikes (fire ele def)

wouldnt be hard to implement I wouldnt think