This is what you need ceramic tweezers for, The reverse ones you just grip over the so-so joint and reflow it and it squeezes all the solid metals together helping the heat spread properly.
What I noticed before using the ceramic tweezers is I have a hard time getting both the xt90 connector and wire side molten at the same time. Having to go in sideways to touch both, once you have the ceramics getting the whole joint to melt at once is much easier.
best tools for holding wires together, and take near 0 heat away from what you are soldering.