I would imagine if one of the first two conditions are met that you would be allowed to cast it upon yourself. It is a spell with a positive effect, like healing, purify and restore limb. It is most likely that they all have similar rules, especially as they have similar wording. I think for RP purposes you would probably be able to use all spells on yourself, including entangle and paralysis. If it doesn’t say you can’t, I’d image that you can.
When dealing with magic you have to take in two things into considerations, does it work OOC and is it too over powered. In some ways it is less powerful to cast it on yourself than someone else because you have either had to spend xp to get ambidextrous or you have slowed the process down by changing weapons. By giving it to someone else, they can go for it immediately so I think the only reason you would want to cast it upon yourself is if you are the only one around, in a tight situation and need to get out or you are in a duel with someone.
Basically I can see no reason why you wouldn’t be able to empower yourself.