If you are feeling the pinch on priests, you might consider alchemizing some Earth gems, building some Temples, and recruiting some cheap priests.
(One of these can really toughen up a province defense (PD), and 2-3 would be really useful if you hit undead or need to keep those rather chaotic Trolls pushing forward.)
Personally, I like to keep about half to two-thirds of my top mages researching. Of course, I also get my butt kicked for not building enough ground troops...
Being too low in research is almost as unhealthy as being too low in dominion. Ulm is not noted for the efficiency of its research, though, so as long as you are not dead last or static/declining you may be ok. You do want to see an elevated growth slope on your research graph. Items that may help include Owl Feather (Air, +3), Lightless Lantern (Fire +6), and Skull Mentor (Death +10).
You might consider saving your Earth gems for the globals. At Cons 5 you are approaching Forge of the Ancients (Cons 7, caster E5). You might want to take another look at Enchantments: both Riches From the Earth (Ench 6, caster E5--$$$!) and Earth Blood Deep Well (Ench 7, caster E6--EEE!) will give you substantial benefits.
I would feel a lot better about handing out Swords of Sharpness (which are not magical!) if I knew my thugs were protected by Gift of Health, but that's just me. If you have a hard-charging knight, you might consider a Shield of Valor. Armor of Virtue would protect your prophet at the cost of occasionally putting him out of position--a flight item would return him to action quickly.