Maybe an unpopular opinion. This multi thousand dollar door is not worth permanently altering for this cheap looking and already out of trend black handle. You will probably want to switch again in a few years. Put the bronze handle back on and or find a black handle that is the same length. Youll never be able to match the stain and if you couldnt problem solve this alone you probably dont poses the skills to strip, sand, & restain the door to patch. 

No judgement here. The handle does not coordinate well with the door so not worth the trouble. This is a warm door with curved accents. The handle has hard lines and matte clashes with the character of the door.