I play single hero army with assasine. It feels good to play a character who rules the map like a demigod and kills armies of dragon as single unit :). And he got mostly all spellschools by killing the other heroes you get over fame.
Actually, my familar use beastmaster tame, too....
Question, for what you want to use your weapon... on cheap units, clubs are weapon of choice. They should do damage as fast as possible, because next round they can be death. On dodge assasine hero, i like swords with starts like, +2 counterattack, +100% crit damage. They get there -armor over the tree ... and shild.
I got it in my single hero assasine dodge army/demigod run. my custommade hero was level 10 when he finished the quest. He never used spells, but with manshild i found a reason to use my realm mana. He had the no mana cost starter item for buffs (in my oppion the strongest item in game). He started the arena quest with level 13 and finshed it with 17, with even killing the golems at the end^^ My advice for manaproblems --> get a mage with familar, crull of the weak and rise sekelto