Using skills need strategy. I think you should plan with a skill effects and its limits. I see no reason to allow cancel such effect.
Yes. but the use of that "strategy" is very limited in Ryzom.
In that case, i think adding more depth into PvP can be a good thing.
It may even force people to "time" by head, the aura and how many second your opponent has it / remain.. can lead to a lot of tactics and ressource management / pressure.
And not the casual "oh noes! my mate dead.. i have 600hp left, lets invu? then you wait.. and pray for a magical rezzu.."
Classic.. boring.. lets improve it!
And .. hey.. Ryzom is missing that really (at least in PvP).