i got my first knife when i was 7-bought it at a yard sale with sme birthday money. it was the little swiss army classic, but i loved the shit out of it. probably not enough for /out/ stuff, though
i'd be reluctant to get a 7 year old a locker, unless the lock is VERY easy to operate-wouldn't want them struggling with the lock and the blade simultaneously. better to just teach them to be respectful of the swinging blade imo.
what about something like this:
>http://www.buckknives.com/product/canoe-knife/0389BRS-B/ pic related. seems versatile.
whatever you decide, have fun with your little sc/out/. i'm looking forward to mine being that age