I dont understand how can you say the tank (Eidelweiss) is not important.It allows to block enemy fire ,it can take several enemies out each turn if you are close and use the mortar ,its can be repaired each 1-2 turns so it keeps attracting enemy fire and leaves some room for your other characters to progress,and sometimes its the only unit capable of fighting big enemies without dying in one turn.For example in the fight witn Maximilian uber-tank and the posterior appearance of Selvaria the Eidelweiis is absolutely crucial ,to take out the turrets of the sides of the tank ,to shoot into the radiator from far if you dont have any lancer near to jump on the tank ,to block the enemy fire and keep your engineer and some lancers alive ,and finally when Selvaria arrives to keep her at bay and dispose of the extra troops she comes with while you reserve some lancers to take out the last radiator.