Spain’s main strengths are an excellent navy and excellent light infantry and cavalry, while they lack heavy infantry and spearmen in the early period. This may be the future or it may be folly, the success or failure of the Spanish king will determine that. France are a powerful kingdom and invading them is perhaps not a wise choice, which leaves a naval-based empire. Obviously, the first priority will be to take the rebel territories to the east and to push the Moors back to North Africa, but beyond that, the objectives are not so clear.
Spain are a relatively united force by recent standards, as most of the Christian kingdoms and fiefdoms are united, but the tight hold that the Moors have on southern Spain and the recent independence of Portugal mean that they are not necessarily a hugely powerful kingdom.