You need the mutations. You can fight as good as you want but you can never be a good monster hunter and killer who survives his job for long.
A Witcher is a mutant who is immune to nrealy every toxin, venom or poison, can't get sick/ill, can see in the darkness and his pulse goes 4 times slower than a normal human. Yeah we saw Ciri fight good, but we also saw her many... maaany times get hit, and nearly died from it (men of Cyprian Wiley, a nromal elve, a "Shuriken", a wolf etc.).
Just let her fight against a monster and she is just slighty hit, but by a venomous monster. A venom a witcher will not harm, or he can wistand. Ciri would get sick, loose a limb, or die. And she also cannot take potions to heal herself or stuff like this, cause potions will kill her or give her a bad life.
Or she is wounded and bleed to death, while a witcher have enough time to dearch for help or get a potion. Due to the slow heart rate Witchers are neraly invisible for monster who go for hearbeat, blood etc. like vampires, Ciri is clearlly visible. As she said to Geralt, in B&W. She fought one Garkin and had big trouble, and this was a non-venomous monster.
Ciri might be able to do the job a bit, but she will die someday, alone in a dark cave or a lonley forest, cause she is not bale to work like a witcher and survives like a witcher. This is what very many gamers seem to forget.
Fair point. Yet still, Ciri was smart enough such that she likely wouldn't engage in a situation where she was... compromised (intellect trumps all). Also, Witchers need mutations because, well, they can't go poof and reappear behind the
"opponent" (barring intellect, speed trumps all, the abilities of Ciri in this context qualify as speed). The short version, Ciri wouldn't approach monsters as a "normal" Witcher would. She doesn't have the same abilities. She has different abilities. She would play to those strengths. Fast reflexes, abnormal strength, heightened senses, great. Compare this to going poof and reappearing in another location. Which is the more powerful ability?