Auto-translated
I'll highlight a few artifacts that are, of course, not composite and are useful in battle.
1) Medal of Vulnerability.
Magic against Black Dragons, blindness against Titans, a little bit of everything. You get the idea.
2) Cloak of Swiftness. +2 to movement on the battlefield. A very useful artifact; with a well-developed strategy, you might not even need to use the speed boost for instant attack.
3) Amulet of Courage. +3 to morale and luck. You can avoid developing the basic corresponding secondary skills.
4) Boots and Gloves of the Traveler. It's always nice to be able to travel further on the game map.
5) Phial of Life, of course. Especially those of Earth and Air. And if you also have these skills developed... ;)