Did Messengers Perform Miracles?

S 6:48 And we do not send commissaries except as bearers of good news and warners. So those who have believed and reformed--there is no fear upon them nor do they grieve.

S 18:56 And we do not send the commissaries except as bearers of good news and warners. And those who have disbelieved argue with falsehood to refute the truth therewith. And they have taken my verses and what they have been warned of as a quip.

Both verses use the non-past, or present tense, 'send'. Why, if the founder of Islam was the last messenger? The unnamed speaker(s) in the two verses state(s) that 'we' don't send commissaries, which are messengers, except as bearers of good news and as warners. So how might a messenger have performed miracles?

Quran speaks of Isa and miracles and Musa supposedly performed them. But then we have the verses above.

Further reading:

Isa's Miracles