Weak verbs in germanic tend to be roughly defined as those verbs taking a "dental" ending, excluding the preterite-present verbs.  There is a misconception that this group consists only of "regular" verbs, but that is another story.

The germanic weak verbs fall into four categories: Those ending in -jan (class I), -on (class II), -an (class III), and -nan (class IV). [what about -en?]  In northeadish most of these classes have fallen together, and class 1 is differentiated from the other classes only in that it undergoes i-umlaut in the present tenses.

1. Class I

Class I weak verbs, sometimes known as -jan verbs, are conjugated as follows:

			pret.	conj.	pres.	subj.	imper.
		ec	racþa	ræcþa	ræca	ræca
	(rakjan)	þū	racþast	ræcþast	ræcst	ræcast	ræc
inf.	ræcɴ	h/s	racþa	ræcþa	ræcaðþ	ræca
ppr.	ræcɴþ	vīt	racþa	ræcþma	ræca	ræcma	ræca
ppt.	racþ	jȳt	racþatþ	ræcþatþ	ræcatþ	ræcatþ	ræcatþ
		vīr	racþм	ræcþм	ræcм	ræcм	ræcм
		jȳr	racþaðþ	ræcþaðþ	ræcaðþ	ræcaðþ	ræcaðþ
		sīr	racþɴþ	ræcþɴþ	ræcɴþ	ræcɴþ

Note that -jan verbs show i-mutation in the past subjunctive as well as the present and infinitive paradigms. Please note that class I verbs are indicated in the reform alphabet by ending in -en instead of -an.

2. Class II

Class II, or -ōn verbs, are usually derived from a noun or adjective.  Various phœnetic and morphosyntactic changes throughout the centuries have made them indistinguishable from Class III weak verbs.

			pret.	conj.	pres.	subj.	imper.
		ec	bevða	bevða	beva	beva
	(bibōn)	þū	bevðast	bevðast	bevast	bevast	bevf
inf.	bevɴ	h/s	bevða	bevða	bevaðþ	beva
ppr.	bevɴþ	vīt	bevða	bevðama	beva	bevma	beva
ppt.	bevaðþ	jȳt	bevðatþ	bevðatþ	bevatþ	bevatþ	bevatþ
		vīr	bevðм	bevðм	bevм	bevм	bevм
		jȳr	bevðaðþ	bevðaðþ	bevaðþ	bevaðþ	bevaðþ
		sīr	bevðɴþ	bevðɴþ	bevɴþ	bevɴþ

3. Class III

Class III weak verbs, or -an verbs, are the most common weak verbs, though many of them have been assimilated into strong verb classes.

			pret.	conj.	pres.	subj.	imper.
		ec	trunða	trunða	truna	truna
	(turnan)	þū	trunðast	trunðast	trunst	trunast	trun
inf.	trunɴ	h/s	trunða	trunða	trunðþ	truna
ppr.	trunɴþ	vīt	trunða	trunðma	truna	trunama	truna
ppt.	trunþ	jȳt	trunðatþ	trunðatþ	truntþ	trunatþ	truntþ
		vīr	trunðм	trunðм	trunм	trunм	trunм
		jȳr	trunðaðþ	trunðaðþ	trunðþ	trunaðþ	trunðþ
		sīr	trunðɴþ	trunðɴþ	trunɴþ	trunɴþ

Class III verbs do not show any sign of i-mutation.

4. Class IV

Class IV weak verbs, or -nōn/-njan verbs, are ostensibly the same as Class I or II verbs, but with -n added to the root. Many of this type of verbs are strong verbs.

			pret.	conj.	pres.	subj.	imper.
		ec	tǣcɴða	tǣcɴða	tǣcna	tǣcna
	(taiknjan)	þū	tǣcɴðast	tǣcɴðast	tǣcnast, tǣcɴst	tǣcnast	tǣcɴ
inf.	tǣcnɴ	h/s	tǣcɴða	tǣcɴða	tǣcnaðþ, tǣcɴþ	tǣcna
ppr.	tǣcnɴþ	vīt	tǣcɴða	tǣcɴðma	tǣcna	tǣcnama	tǣcna
ppt.	tǣcnðþ	jȳt	tǣcɴðatþ	tǣcɴðatþ	tǣcnatþ, tǣcɴtþ	tǣcnatþ	tǣcnatþ, tǣcɴtþ
		vīr	tǣcɴðм	tǣcɴðм	tǣcnм	tǣcnм	tǣcnм
		jȳr	tǣcɴðaðþ	tǣcɴðaðþ	tǣcnaðþ, tǣcɴþ	tǣcnaðþ	tǣcnaðþ, tǣcɴþ
		sīr	tǣcɴðɴþ	tǣcɴðɴþ	tǣcnɴþ	tǣcnɴþ

5. Class V

Class V weak verbs, or -ǣn verbs, have become indistinguishable from Class I verbs.