TomOBedlam;
Some options for weapon growth with PC:
1) Create the spirit as a PC and keep track of the levels and let the spirit grow in level as the PC does. Or have the spirit grow in some multiple of the PC's level. So at 1st the spirit is 2nd level, at 2nd the spirit is 4th level, etc.
2) Same as above but let the spirit roll dice like gaining a spell list and have him grow in level equal to the spell limit. So at the beginning of the game the spirit is 5th level and gets a specific number of points to pay for level gain and they roll d100 add the vale to see if they gain the next highest tier of levels.
3) Have the spirit gain levels as the PC finds other items of the smith. So hammer spirit is 5th level, find girdle adds +2 levele, boots +1 level, gauntlets +3 levels, helm +5 levels, apron +3 levels, tongs +1 level, find forge he built +10 levels while in that location.\
4) Unlock spirit levels after specific actions. ie bind a fire spirit and do X with it. Now the spirit remembers more of its self and advances from level 10 to 15th.
Other options:
1) Give the PC extra DP they can only spend in a specific set of skills. Keep good records so you can see what happens.
2) Let the item cast the spells through the PC. ie the spirit has to be attuned to the wielder to be able to dram mana through him. ie everybody holds small amount of mana but it does not stay with them. The spirit can take those small bits and store them as a spell caster.
3) Give a set amount of DP to gain spells like a spell caster. But can only be cast while he has the item. You can also get the spirit to be unhappy with the wielder and refuse to cast spells.
4) Use some abstract system to allow the caster to cast spells. ie the wielder cuts himself for 20 hits and can now cast spells to 20th level. Or maybe a sacrifice something to cast spells.
5) I am not that up on RM rituals but maybe you use those as a guide and the spirit aids the PC in the ritual.
Keep them coming the ideas are flowing. I hope they are or might be helpful.
I have always loved multi items or items that can do multiple things. Such as the old Rod of Lordly Might. Or maybe collecting the dragon orbs.
Also does not SW have powerful items like this? You also may ask around as at one time there was going to be a treasure guide for SW. If it did not make it to print maybe some of the info is still out there with someone.
MDC