You are mistaken about shields - as you play you will acquire literally thousands of eight hour shields without effort. Some come from daily loyalty rewards, some while hitting Ubers and from various other activities also. You will soon find that you can maintain a shield virtually all the time.
Domain guards are scarse. You get some as rewards in various events, for example reaching the final checkpoint in the recently completed Trick of the Gods event yielded 12.
Runic coins appear as rewards in the final checkpoints of numerous events and you will get a dribble from quests. Once you accumulate 1 million keep those as a float because an item comes up about every other season which allows you to buy 1.5 million for 1 million. Otherwise my own prefeerence is to use runic coins to purchase town skins. It takes a while to accumulate the 2 million or 4 million coins required but not so very long if you are an active player.
It is irritating to have your town looted on an occasion where your shield is down. But it is no very big deal. You lose troops and resources but those are easily replaced. Your buildings, hero, shaman, hero and shaman skills and equipment, knowledge, aesir etc. etc. are all undamaged and it is those things which you have worked to develop.
Good luck.
