How to win with a “weak” Knight?

Yes, along the route from the castle to the foundry, a line of heroes is formed. When enough gold accumulates, swordsmen (pikemen) are purchased, passed from one hero to another, and so on, until they are upgraded. From there, they are also passed along in a chain to the main hero (squire), who no later than day 131 (preferably 127) captures the top (starting) castle of the Warlock. Depending on the availability of sulfur (presumably 20 will be enough), stones, and gold: if there is enough to build a Green Tower, then it is necessary to capture it on day 127 and build it; if there is definitely not enough (by the way, there is an external market along the way), then it can be done on day 131 (see the yet-to-be-written article "Heroic Numerology" for more details).