Copying target permanent's ability sounds really vague, and also complicated. xD Does it copy passive abilities, like a Sundial's nocreaturesattackthisturn effect? The active abilities, like Sundial's Hasten? Both? Will a Sundial-fused RS be destroyed after one turn? What happens when you target a weapon/shield? Will the attack stats stack, and will Rune Sword both attack and offer DR?
I also think there's going to be a permanent where this will have too much synergy with.
I think it's fine as it is. Take Mutation for example. The description says "Mutate the target creature into an abomination, unless it dies... or turn into something weird." If you were new to the game, what would you make out of this? It would sound complicated to me. But there's a reason it's in the game, right?
Interesting concept. xD For the Life ability though, I can only think of 1 creature with less than 3 attack...