| Dracomicron |
I know that you can add fusion effects at certain spell levels, but I don't remember there being a specific ruling on fusion seals. Don't you need to wait 24 hours for a fusion seal to take effect? No Junksword lasts that long.
If I had to make a ruling on what level a Junksword is, I'd either go with caster level or the minimum level necessary to cast that particular Junksword spell (4th level for Junksword 2). I'd have to think about it.