I haven't seen this mentioned anywhere so I thought I'd make a post about it.
On the Xbox 360 the only way to use multiple Combat Arts of the same aspect is to put them in a combo, otherwise every CA of the same aspect you just used has a timer put on them. But if you put them in a combo, you can use 2 (three if you upgrade) aspect Combat Arts at a time.
This seems like a pretty important tip for people that I never ready anywhere in the Sacred 2 wiki. Is it the same for PC? It took me a while to figure this out when I got annoyed of seeing a timer pop up on Combat Arts that I wanted to use.
Something I do now with every toon is to assign the main attack Combat Arts of each aspect into three combo's, one aspect per combo.
Then assign the weapon attack combo to Y, Area of Effect stuff to B, and the other to A. I Reserve X for either the weapon, or in my TG's case Battle Extension.