Back on the island one of the most important skills, more important than shooting sometimes, was watching. Observing. Understanding.
Oliver was no longer on an island anymore, but old habits were hard to fight, especially when they had made him survive.

Now he found himself observing hands – marble skin, pink fingernails. One of them carried a yellow smiley. They were moving swiftly, almost elegantly. It reminded him of his own gym training – there was a certain passion in her movements.

Oliver smiled as he realized that though in a high tech world, Felicity's real weapons were her hands. Hands and brains. Just like him.
They were not that different at all.