Amalgamation

This Artifact can tack the form of any weapon and magical item you merge with the amalgamation. To merge a weapon or magical item you must pour mana into the artifact and let it consume the item. In this process the player will roll a d100 and the higher the number the player rolls the better the consumption goes

if the player rolls good enough, determined by the DM, the process work as it should and  no damage is done 

If the player fails, The DM can decided a punishment 

This consummation of a item can be split into two separate task, A new form or a new effect, 

if you add a form you can tack a action to switch the base weapon of the artifact

if you add one effect you give the artifact a new effect that the consumed item had, this grows the artifact and if the DM thinks the player has made this artifact too powerful they can give disadvantage on any more consummation and or give a negative modifiers to the rolls

You may attempt to add a affect once per day (the DM can change this to be longer or shorter) 

Notes: The DM can use some hidden effects to balances this artifact. some effects can be / effect one, this weapon is unstable and merging too many effects in a short deration can cause negative consequences determined by the DM, Examples include vulnerabilities, Disadvantage on some checks or saves, Adding a negative modifier to a check or save, etc. effect two, This weapon has grown and adapted, This growth can result in growing a ego or making it have more charges every dawn. If the artifact grows a ego the DM can pick how it treats the wieldier. and if you want to the DM can pick and decided on more effects, Anyone, When you attune to this weapon you can never destroy the bond though normal means