As far as I know, the only real-world country (in Medieval Europe, which is what I'm basing these countries on by default) that had everyone practise every year was England, and that was just with the bow. Altranor herself has a reasonably large army of professional soldiers, but the main fighting force comes from all the vassals who are required to provide fighting men and equipment in times of war. There's never been a shortage of eager young recruits with dreams of gold and glory, but if additional soldiers are needed on short notice, there's always mercenaries and - if the need is exceptionally dire - adventurers.

Of course, the fantasy elements of the setting muddles things a bit. A church might decide that your war coincides with the will of their god, and offer the services of their templars and priests. An ogre farmer has neither the lack of fighting skill nor the morale problems of a human, and are very tempting to draft - although that still turns an income into an expense - and wizards tend to be either commissioned officers or mercenaries. If your ruler happened to have a friendly relationship with a dragon (of which the Fanged Island has mercifully few), you would have an incredible terror weapon available, and so on.

Now, I'm not a historian by any stretch of the imagination, so I could certainly be wrong. These are the assumptions I'm running with, though.