Note: the moment she realized her armor was useless against Lancer's Red Spear, Artoria prepared to show off some moves.
First, she removed her armor, revealing the formal dress beneath it.
As expected of King Arthur with all A-ranks—even in that regard, she was an A.
Once the weight of her armor was gone, Artoria's movements became noticeably more agile. However, Lancer wore a strange smile.
She had fallen for it!
Without drawing attention, Lancer shifted toward the spot where he had discarded his Short Spear. While using his long spear to block the Shining Sword in Artoria's hand, he kicked the Short Spear up.
Only then did Artoria realize that his stance with two spears had not been a feint. Both weapons were truly killing blows!
Her Instinct skill allowed Artoria to realize she had been tricked faster and take remedial action in time. At once, she swung her sword at the hand Lancer used to grip the Short Spear, intending to sever his tendons and make him drop it.
But her own hand tendons were slashed as well!
Shirou slapped his face. So you ate my warning beside Galahad's holy shield?
"Irisviel, heal me."
"I can't. I already tried healing you, but it had no effect."
"It can't be healed?"
"Your courage in realizing that armor was useless before my Red Rose of Certain Victory is worthy of praise. But removing your armor so rashly was far too impulsive. Otherwise, you could have blocked this Yellow Rose of Certain Destruction."
Now that the effect of his Noble Phantasm was known to his opponent, there was no point in continuing to conceal its true name.
Lancer resumed the stance he had taken at the start of the battle. His opponent was formidable; even injured, she would not be so