Current: no true siege action in a month (I think).
Recommendation: incentivize siege through a tiered bonus to castle ownership. Standard ownership benefits each week but multiply those benefits x1.2 for week 2 of holding, 1.3 for week 3, 1.4 for week 4, etc.
Recommendation: increase the number of pledges in an alliance to increase participation in siege. There are a number of smaller pledges that may wish to join but don't have the numbers to contribute and aren't allied to the seiging/defending group because of the alliance cap of 2.
Recommendation: siege stat related bonuses for most kills, my heals, most assists, etc using the data already being tracked. Bonuses could be Adena, leaf blessings, discount at shops, event foods, fancy boots, anything really
Recommendation: big bonus for taking the castle from the incumbent. This incentivizes smaller pledges joining the attackers and making the defending group at a (theoretical) disadvantage