Some notes:

Four non-PC Imperial evokers mentioned so far, but there may be more. 
#1 is merely a farseer. Not a perfect one. I.e. those using that one will have to have some knowledge to make sense of what is seen. If you don't know which company is where, you won't be able to tell them apart. Not yet implemented other flaws into this relic. If it has more appearances, we'll do that over time.
#2 turns arrows into bolts of fire, #3 turns arrows into a shiny, unspecified metal. They maintain their trajectory and speed. A poorly aimed arrow still won't hit better after passing through such a field. Fields only work one way. Arrows passing through the other way aren't boosted. Might be they "punch holes" in the field.
#4 is the most powerful. He can create focused, mono-directional ripples in the ground, akin to earthquakes, but on the surface. Old Kingdom foundations are not possible to topple with this power. Again, not yet fully equipped with flaws.