Please help (old returning) player with holy symbol questions

Just started playing again after many many years. Playing D&D encounters. I want to stay within the standard rules. I have not magic items.

I'm a level one cleric and I get to choose one level 5 or lower magic item as part of a encounter reward. I have superior implement training in Astral Holy Symbol.

I really like the Mace of Bane (Dragon 383, Page 69). This is a +1 mace that says it "can also be used as a holy symbol".

My question is, can I use my non-magical Astral Symbol when doing ranged attacks and the mace when doing weapon/power attacks? I'm not suggesting the bonuses "stack" but since one is a weapon and one is a symbol, could I choose to use one or the other per attack? If yes, does it take some actions (minor/standard) to switch? Im mean the symbol is around my neck and the mace is in two hands.

If not, is there a way to make the Mace of Bane also have the non-magical superior implement powers?

If neither of these is possible, then I guess I would just pick a magical superior implement such as "+1 Astral Symbol of Holy Nimbus"?. On radiant attackes this would do +3 damage? (+1 enhancement, +2 superior implement)? Other suggestions of a better level 5 or lower holy symbol?

Thanks for the help!

Holy symbols are worn and don't have to be wielded to be used, so you can switch between a symbol-weapon and a standard symbol without using actions (IMO).

There aren't superior implement versions of weapon type implements (except staff, and dagger in a dragon article about sorcerors) so you can't at present put superior implement properties into a mace - unless your DM allows it anyway.