Fate/Zero

[Ryllharu]

How much prana would it burn if Saber ever used it herself to protect her from a lethal blow or a noble phantasm as strong as Excalibur?

edit: I think my point stands. Saber's weakness is how strong she is.

Different classes require different strategies. One isn't weaker than the other. Archer and Lancer are best used by a supporting mage, Berserker requires only an energy source, Rider is mixed. Assassin requires demands someone intelligent, always thinking of strategy. Caster is best with a Master that acts as a protector, due to their class' weakness to direct confrontations. Saber works both ways, but this Saber is better off with just a battery, like Berserker.

[David75]

.....but this Saber is better off with just a battery, like Berserker.

A battery and a very strong willed master.
Her will to fight, go head on into traps and even despising (almost) her master when he's a pure strategist like Kiritsugu really means trouble.